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anonymous

  • 5 years ago

0=-4t^2+20t+1 i need to figure out wat t is

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  1. anonymous
    • 5 years ago
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    Have you learned the quadratic formula?

  2. anonymous
    • 5 years ago
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    yea but dat aint working it would be a=4 b=-20 c=1 can u try

  3. anonymous
    • 5 years ago
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    a = -4 b = 20 c = 1

  4. anonymous
    • 5 years ago
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    yea

  5. anonymous
    • 5 years ago
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    im trying 2 figure dis out

  6. anonymous
    • 5 years ago
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    (h(t)=-16t^2+vt+c where h is the approximate height in ft t is the time in motion in seconds v is the initial upward velocity in ft per second and c is the initial height in ft) A baseball player hits a pitched ball when it is 4ft above the ground the initial upward velocity is 80ft/s how long will it take for the ball to hit the ground???

  7. anonymous
    • 5 years ago
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    im stuck on the step with the quadratic formula

  8. anonymous
    • 5 years ago
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    So what is the initial velocity?

  9. anonymous
    • 5 years ago
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    Plug that in for v. What is the height above the ground? Plug that in for c.

  10. anonymous
    • 5 years ago
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    v is 80

  11. anonymous
    • 5 years ago
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    And c?

  12. anonymous
    • 5 years ago
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    by-bye polpok

  13. anonymous
    • 5 years ago
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    c is 4

  14. anonymous
    • 5 years ago
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    0=-16^2+80t+4 simplified its 0=-4t^2+20t+1

  15. anonymous
    • 5 years ago
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    Yep.

  16. anonymous
    • 5 years ago
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    but i need t

  17. anonymous
    • 5 years ago
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    Ok so using the formula for the quadratic, what is a, b, and c.

  18. anonymous
    • 5 years ago
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    \[0 =at^2 + bt + c \implies t = \frac{-(b) \pm \sqrt{(b)^2 - 4(a)(c)}}{2(a)}\]

  19. anonymous
    • 5 years ago
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    a=-4 b=20 c=1

  20. anonymous
    • 5 years ago
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    yea but idk y i keep getting really big numbers wat do u get

  21. anonymous
    • 5 years ago
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    t has 2 be 5.1s or 1s or 2s,3s

  22. anonymous
    • 5 years ago
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    I got -0.049509756796392246, and 5.049509756796392

  23. anonymous
    • 5 years ago
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    Are you forgetting to divide by -8?

  24. anonymous
    • 5 years ago
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    tell me exactly how 2 put it in my calculator cuz everytime i do i get large #'s and yes i put divide y -8

  25. anonymous
    • 5 years ago
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    Start with the part under the square root

  26. anonymous
    • 5 years ago
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    so dont put -20 first

  27. anonymous
    • 5 years ago
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    20*20 - 4*(-4)*(1)

  28. anonymous
    • 5 years ago
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    What do you get for that part

  29. anonymous
    • 5 years ago
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    416

  30. anonymous
    • 5 years ago
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    Now take the square root of that

  31. anonymous
    • 5 years ago
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    20.3

  32. anonymous
    • 5 years ago
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    Ok, now you have 2 solutions: \[x = \frac{-20 \pm 20.3}{2(-4)}\]

  33. anonymous
    • 5 years ago
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    Oh, and you didn't round up.. I think it's 20.396 or 20.4

  34. anonymous
    • 5 years ago
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    im still getting 50.75

  35. anonymous
    • 5 years ago
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    -20 + 20.4 = ? -20 - 20.4 = ?

  36. anonymous
    • 5 years ago
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    2(-4) = ?

  37. anonymous
    • 5 years ago
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    .4

  38. anonymous
    • 5 years ago
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    -8

  39. anonymous
    • 5 years ago
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    ok so u dont multiply the -20 to the 20.4/-8

  40. anonymous
    • 5 years ago
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    No, you add and subtract them

  41. anonymous
    • 5 years ago
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    (-20 plus or minus 20.4) / -8

  42. anonymous
    • 5 years ago
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    i got -0.5

  43. anonymous
    • 5 years ago
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    There's one more possibility.

  44. anonymous
    • 5 years ago
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    nope i got -17.45

  45. anonymous
    • 5 years ago
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    and -22.55

  46. anonymous
    • 5 years ago
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    (-20 - 20.4)/-8

  47. anonymous
    • 5 years ago
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    -0.05 is one option.

  48. anonymous
    • 5 years ago
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    But the other one is positive

  49. anonymous
    • 5 years ago
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    ok i got u now wow thanks but its weird how i cant put the whole thing in the calculator

  50. anonymous
    • 5 years ago
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    Because the order matters

  51. anonymous
    • 5 years ago
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    Plus plugging the whole thing in at once makes it harder to find where you made your mistake. Just put in each piece at a time.

  52. anonymous
    • 5 years ago
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    ok can u help me wit another one

  53. anonymous
    • 5 years ago
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    probably

  54. anonymous
    • 5 years ago
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    using the same formula a flare is launched from the deck of a life boat 4ft above the water surface the initial upward velocity is 80ft/s after how many seconds will the flare be 100 ft above the water surface

  55. anonymous
    • 5 years ago
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    So how would you set this one up?

  56. anonymous
    • 5 years ago
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    h(t)=-16t^2+vt+c where h is the approximate height in ft t is the time in motion in seconds v is the initial upward velocity in ft per second and c is the initial height in ft

  57. anonymous
    • 5 years ago
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    i got 100t=-16t^2+80t+4

  58. anonymous
    • 5 years ago
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    it's just 100, h is the height.

  59. anonymous
    • 5 years ago
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    so \[100 = -16t^2 + 80t + 4\]

  60. anonymous
    • 5 years ago
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    ok wat next

  61. anonymous
    • 5 years ago
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    move the 100 to the other side so it equals 0 and then use the quadratic formula again.

  62. anonymous
    • 5 years ago
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    by subtracting 100 from both sides that is

  63. anonymous
    • 5 years ago
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    0=-4t^2+20+24

  64. anonymous
    • 5 years ago
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    4-100 is -196, not positive

  65. anonymous
    • 5 years ago
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    i got 3

  66. anonymous
    • 5 years ago
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    err -96 rather

  67. anonymous
    • 5 years ago
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    well den dis aint working now idk u do it

  68. anonymous
    • 5 years ago
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    You did it right, I don't know how, but 3 is one answer. There is another answer

  69. anonymous
    • 5 years ago
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    If you used -4t^2+20+24 You should have gotten (-1 and 6) though

  70. anonymous
    • 5 years ago
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    But the correct formula -4t^2+20t-24 = 0 gives one of the solutions being 3 and the other being 2

  71. anonymous
    • 5 years ago
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    the answer can only be 1s or 2s,3s

  72. anonymous
    • 5 years ago
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    show me ur formula

  73. anonymous
    • 5 years ago
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    \[0=-4t^2 + 20t - 24 \implies t = \frac{-20 \pm \sqrt{20^2 - 4(-4)(-24)}}{2(-4)}\]

  74. anonymous
    • 5 years ago
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    ok i got dat but now getting big numbers again

  75. anonymous
    • 5 years ago
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    Do the part under the square root first

  76. anonymous
    • 5 years ago
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    \(20^2 - 4(-4)(-24)\)

  77. anonymous
    • 5 years ago
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    16

  78. anonymous
    • 5 years ago
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    and the square root of 16 is?

  79. anonymous
    • 5 years ago
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    4

  80. anonymous
    • 5 years ago
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    Ok, and what's the denominator? 2(-4)

  81. anonymous
    • 5 years ago
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    -8

  82. anonymous
    • 5 years ago
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    polpak, i have some confusion. check your equation once again

  83. anonymous
    • 5 years ago
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    So you have two solutions: (-20 + 4)/-8 and (-20 - 4)/-8

  84. anonymous
    • 5 years ago
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    for the first one you have -16/-8 and the second is -24/-8

  85. anonymous
    • 5 years ago
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    omg thanks

  86. anonymous
    • 5 years ago
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    Hrm India?

  87. anonymous
    • 5 years ago
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    oh whoopse

  88. anonymous
    • 5 years ago
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    No.. wait, that's right

  89. anonymous
    • 5 years ago
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    ok linda dis is my question create ur own i need help 2 get off mines

  90. anonymous
    • 5 years ago
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    no, its alright now. i don't how but the latex code was not properly loaded and the \[-4t ^{2}+20t-24 \] was looking like \[-4t ^{2}-20t-24 \]

  91. anonymous
    • 5 years ago
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    ah. ok

  92. anonymous
    • 5 years ago
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    a basketball player shoots the ball with an initial velocity of 20ft/s the ball is 6ft above the floor wen it leaves her hands how long will it take for the ball to reach the rim of the basket 10 ft above th floor on its way down

  93. anonymous
    • 5 years ago
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    can u check the answer i get

  94. anonymous
    • 5 years ago
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    i cant do \[\sqrt{-21}\]

  95. anonymous
    • 5 years ago
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    so how do i do dis problem

  96. anonymous
    • 5 years ago
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    it is a imaginary number!!!! it will come \[i \sqrt{21}\]

  97. anonymous
    • 5 years ago
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    does dat equal -1

  98. anonymous
    • 5 years ago
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    or 1

  99. anonymous
    • 5 years ago
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    \[-1 = i ^{2}\]

  100. anonymous
    • 5 years ago
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    i=1 right

  101. anonymous
    • 5 years ago
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    no, it ain't right. i is nothing but an imaginary number. it can not be solved. it has to be written i only.

  102. anonymous
    • 5 years ago
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    well it has 2 be possible cuz there is no i answer on dis paper

  103. anonymous
    • 5 years ago
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    one thing, time can't be negative.

  104. anonymous
    • 5 years ago
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    your solution seems wrong!!!

  105. anonymous
    • 5 years ago
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    i have 0=-4t^+5-1

  106. anonymous
    • 5 years ago
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    \[-4t ^{5}-1\]

  107. anonymous
    • 5 years ago
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    do you want to write this equation???

  108. anonymous
    • 5 years ago
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    my bad 0=-4^2+5-1

  109. anonymous
    • 5 years ago
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    i know the answer has 2 be 1 or 1.65 but idk y it aint working

  110. anonymous
    • 5 years ago
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    still something wrong in the equation. there is no "t"

  111. anonymous
    • 5 years ago
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    0=-4t^2+5t-1

  112. anonymous
    • 5 years ago
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    yes, the equation is giving t = 1 and o.5

  113. anonymous
    • 5 years ago
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    how uget dat did u use the quadratic formula

  114. anonymous
    • 5 years ago
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    hmm, yes

  115. anonymous
    • 5 years ago
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    how cuz i got -41/-8 + or - 5

  116. anonymous
    • 5 years ago
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    you must be wrong cuz i used calculator to solve.

  117. anonymous
    • 5 years ago
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    i did 2 show me wat u put in

  118. anonymous
    • 5 years ago
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    \[\frac{-b \pm\sqrt{b^2-4ac}}{2a}\]

  119. anonymous
    • 5 years ago
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    i know dat wat numbers did u end up wit

  120. anonymous
    • 5 years ago
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    1 and 0.5

  121. anonymous
    • 5 years ago
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    will be the answer

  122. anonymous
    • 5 years ago
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    no i mean like wat was b^2-4ac

  123. anonymous
    • 5 years ago
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    0=-4t^2+5t-1 put a = -4 b = 5 and c = -1

  124. anonymous
    • 5 years ago
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    i did i keep getting -41 on top

  125. anonymous
    • 5 years ago
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    \[b ^{2}-4ac = 5^{2}-4(-4)(-1)\]

  126. anonymous
    • 5 years ago
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    you will get 9

  127. anonymous
    • 5 years ago
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    i was putting -5^2

  128. anonymous
    • 5 years ago
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    -5^2 will also be 25. the sign doesn't matter when there is a square

  129. anonymous
    • 5 years ago
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    thanks

  130. anonymous
    • 5 years ago
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    my pleasure!!!

  131. anonymous
    • 5 years ago
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    0=-16t^2+27+1 need some help

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