## anonymous one year ago Evaluate the expression below when x = -1. 2x2 − 5 x + 9

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1. anonymous

2. anonymous

3. anonymous

??

4. anonymous

??

5. anonymous

hello??

6. Nnesha

replace x by -1

7. anonymous

8. Nnesha

nope

9. anonymous

10. confluxepic

Just substitute it.

11. Nnesha

$2(-1)^2 -5$ substitute value and then solve !

12. anonymous

i dont know how to substitute because we have never ever had a half decent math teacher

13. Nnesha

$$\color{blue}{\text{Originally Posted by}}$$ @Nnesha $2(-1)^2 -5$ substitute value and then solve ! $$\color{blue}{\text{End of Quote}}$$ like this just replace x and plug -1 now solve what is square of (-1) ?

14. Nnesha

(-1)^2 is same as -1 times -1 = what ?

15. anonymous

i dont know what the answer is

16. confluxepic

For example x=12. 3(x)+2=y 3(12)+2=y <--------------------------------- 36+2=y | 38=y | | See how I substituted x as 12 to solve the example equation? -------

17. Nnesha

what is -1 times -1 = ??

18. confluxepic

Arrow line messed up.

19. anonymous

-1?

20. Nnesha

negative times negative = positive negative times positive = negative so negative 1 times negative 1 = ?

21. Nnesha

@sheppard18 what do you think ? -1 times -1 = ??

22. anonymous

1?

23. Nnesha

yes right

24. anonymous

1 is not a choice

25. Nnesha

$2(-1)^2 -5$ $2(1)-5 =what ??$

26. Nnesha

i didn't say one is the answer

27. anonymous

-7/8, -3/8, -1/8, -1 theses are the choices we have

28. anonymous

-3?

29. confluxepic

Example: x+2=y You know that x is 1 but you need to find out y. So you put $$\color{red}{x~as~1}$$ in the equation. $$\color{red}{(1)}$$+2=y. 1+2=3 so y=3. Get it?

30. Nnesha

yes that's right! remember PEMDAs rule Parentheses exponent MD) MULTIPLY OR DIVIDE AS ) ADD OR SUBTRACT

31. anonymous

32. anonymous

were from tug valley we dont know much

33. Nnesha

you have to learn in order to know something

34. anonymous

are teacher does nothing but sleep in class

35. anonymous

and calls the office on our class because our class is so mean

36. Nnesha

alright thanks for joining os here we will teach u no direct answers!!

37. anonymous

well how do i do it

38. Nnesha

$$\color{blue}{\text{Originally Posted by}}$$ @estepp33 -3? $$\color{blue}{\text{End of Quote}}$$ yes right

39. anonymous

40. Nnesha

substitute given x value which is -1 $\huge\rm 2(-1)^2 -5$ take square of -1 which is 1 (-1 times -1 = 1) $2(1)-5 = ???$

41. anonymous

that comes out to be -3 what do we do with the -3

42. Nnesha

that's the answer of first one

43. Nnesha

i guess your question is $\frac{ 2x^2 -5 }{ x+9 }$ right it's a fraction ?

44. anonymous

it will be a fraction or a whole numbner

45. anonymous

yes its a fraction i need help with the bottom now

46. Nnesha

so why you didn't tell me ?? use */* for fraction so we know it's a fraction

47. Nnesha

i thought those are 2 different expression

48. Nnesha

$\huge\rm \frac{ 2\color{blue}{x^2} -5 }{ \color{blue}{x}+9 }$ just like we did before replace x by -1

49. anonymous

50. Nnesha

that's right

51. anonymous

i got 8

52. Nnesha

yes the denominator is 8

53. anonymous

can u help me with this question The simplest form of the expression 4m−17m2−16+3m−11m2−16 has in the numerator and in the denominator.

54. Nnesha

and how do i know what is in the numerator and what is in the denominator use the equation and type ur question

55. anonymous

i dont know

56. Nnesha

what ?

57. Nnesha

$\huge\rm 4m−17m^2−16+3m−11m^2−16$ like this ?

58. anonymous

4m-17/m^2-16+3m-11/m^2-16

59. anonymous

that is the fraction ^

60. anonymous

4m-17/m^2 this is the fraction

61. Nnesha

$\huge\rm \frac{ 4m-17 }{ m^2 } -\frac{ 16+3m-11 }{ m^2 -16 }$ like this ?

62. anonymous

yea

63. anonymous

m^2-16 on both bottom sides

64. Nnesha

$\huge\rm \frac{ 4m-17 }{ m^2 -16} -\frac{ 16+3m-11 }{ m^2 -16 }$ looks good ?

65. anonymous

yes

66. anonymous

no

67. Nnesha

68. anonymous

4m-17/m^2-16 + 3m-11/m^2-16

69. anonymous

the minus sign should be plus and the 16 on top on the right shouldnt be there

70. Nnesha

$\huge\rm \frac{ 4m-17 }{ m^2 -16} +\frac{ 3m-11 }{ m^2 -16 }$ find common denominator? what is common denominator ?

71. anonymous

16

72. anonymous

16?

73. anonymous

??

74. Nnesha

1not just 16 m^2 -16 should be together $\huge\rm \frac{ }{m^2 -16 }$ so m^2 and -16= common denominator

75. anonymous

ok what do i do

76. Nnesha

now bec denominator of both fraction are same as common denominator so just carry down the value of numerator $\huge\rm \frac{ 4m-17+3m-11 }{ m^2 -16 }$ now combine like terms 4m-17+3m -11= what ?

77. anonymous

-21

78. Nnesha

how did yo uget -21 ?

79. anonymous

i done 4-17+3-11

80. Nnesha

what are LIKe terms ?

81. Nnesha

you can't combine 4m with -17 bec there are not the same

82. anonymous

3 and 4

83. Nnesha

add coefficient of same variable yes right 3m and 4m combine them

84. Nnesha

3m+4m =what ? -17-11= ?

85. anonymous

7 and -28

86. anonymous

??

87. Nnesha

$\huge\rm \frac{ 7m -28 }{ m^2 -16 }$ now factor 7m-28 what is common factor ?

88. Nnesha

nd apply difference of square for the denominator part $\rm a^2 - b^2 = (a+b)(a-b)$

89. anonymous

what do i do with that

90. Nnesha

alright first factor the numerator 7m-28 what is common factor ?

91. anonymous

is it m+4

92. anonymous

??

93. Nnesha

for which one ?

94. anonymous

the right one

95. Nnesha

alright 7m-28 what is common in these both terms ??

96. anonymous

i got to go im going home

97. anonymous

thanks for the help

98. anonymous

99. anonymous

100. Nnesha

7m -28 7 is common so take it out $7( ????)$ now divide both terms by 7 and write your answer in the parenthses

101. anonymous

102. Nnesha

nope not just m+4

103. Nnesha

m^2 -16 = w hat ?

104. anonymous

?

105. Nnesha

m^2 -16 what are factor of this equation

106. anonymous

it said error

107. Nnesha

apply difference of square method $\huge\rm a^2 -b^2 = (a+b)(a-b)$

108. Nnesha

what ? who said error ?

109. Nnesha

apply difference of square method $a^2 -b^2 =(a+b)(a-b)$

110. anonymous

the caa

111. anonymous

calculator

112. Nnesha

don't use calculator take square root of first term and 2nd term |dw:1434382762154:dw|

113. anonymous

?

114. Nnesha

Take square root of first term and take square root of 2nd term write ur answer in both parentheses (sqrt of 1st term PLUS sqrt of 2nd term) (sqrt of 1st term - sqrt of 2nd term ) example |dw:1434382868450:dw|

115. anonymous

(m+1) (2-6)

116. Nnesha

that's an example m^2 - 16 = what ??

117. anonymous

idk

118. Nnesha

difference of square method have to when both terms are perfect square root and there should be negative sign for example x^2 - 36 1st term =x^2 2nd term =36 square root of first term is =x square root of 2nd term is = 6 now write these in parentheses|dw:1434383072396:dw|