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EmmaH

  • 3 years ago

PLEASE HELKP ME IM BEHIND PLEASE EXPLAIN STEPS AND I WILL GIVE YOU A MEDAL. Factor the trinomial: 4x^2 - 8x - 5 (2x + 1)(2x - 5) (4x + 1)(x - 5) (4x - 5)(x + 1) prime

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  1. precal
    • 3 years ago
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    |dw:1360095374158:dw|

  2. precal
    • 3 years ago
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    I am going to teach you a method called slide and divide take the 1st number and slide it to the back by multiplying it to the last number

  3. EmmaH
    • 3 years ago
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    so -20

  4. precal
    • 3 years ago
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    |dw:1360095443097:dw|

  5. precal
    • 3 years ago
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    we know x times x is x to the second power we are using 10 and 2 because 10 times 2 is 20 but we need to subtract them to get 8 the minus sign in front of 20 tells us to subtract those two numbers

  6. precal
    • 3 years ago
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    |dw:1360095532927:dw|

  7. EmmaH
    • 3 years ago
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    |dw:1360095517633:dw| what happened there?

  8. precal
    • 3 years ago
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    +2-10 gives us -8 we need -8x

  9. precal
    • 3 years ago
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    last step is to divid the number back in

  10. precal
    • 3 years ago
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    |dw:1360095575598:dw|

  11. precal
    • 3 years ago
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    because 1/2 is a decimal we will now take the 2 and move it in front of x and drop the 1

  12. precal
    • 3 years ago
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    |dw:1360095620919:dw|we are done

  13. EmmaH
    • 3 years ago
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    hey please slow down

  14. precal
    • 3 years ago
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    you can read through each step until you learn the pattern

  15. EmmaH
    • 3 years ago
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    |dw:1360095653585:dw| you lost me here

  16. EmmaH
    • 3 years ago
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    i dont understand what you did

  17. precal
    • 3 years ago
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    |dw:1360095676993:dw|you have to list all of the products of 20

  18. precal
    • 3 years ago
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    the sign in front of 20 tells you to subtract them, you are looking for the middle term

  19. precal
    • 3 years ago
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    |dw:1360095746738:dw|

  20. precal
    • 3 years ago
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    |dw:1360095763812:dw|use 2 and 10

  21. EmmaH
    • 3 years ago
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    but that would be positive 20

  22. precal
    • 3 years ago
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    |dw:1360095780117:dw|these are your sign choices

  23. precal
    • 3 years ago
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    do the signs separate

  24. precal
    • 3 years ago
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    |dw:1360095836253:dw|

  25. EmmaH
    • 3 years ago
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    ok look i found -2, and 10 to be the correct factors all i wanted to know was how to inser that into the equation and solve

  26. precal
    • 3 years ago
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    |dw:1360095897773:dw|

  27. precal
    • 3 years ago
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    2 must be positive and 10 must be negative

  28. precal
    • 3 years ago
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    |dw:1360095963415:dw|

  29. EmmaH
    • 3 years ago
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    ok im sorry i made a huge mistaje when writting this i didnt use the ^

  30. EmmaH
    • 3 years ago
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    look at the prob again

  31. precal
    • 3 years ago
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    does not change my answer since I did use the correct notation

  32. EmmaH
    • 3 years ago
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    can you please not use the drawing i cant read it or understand it..im sorry im just so confused at how you got your answer and i understand if you want to just give up on me..

  33. precal
    • 3 years ago
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    sorry need to go, repost your problem someone will come help you

  34. EmmaH
    • 3 years ago
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    alright

  35. rosedewittbukater
    • 3 years ago
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    4x^2 - 8x - 5 Ok so I'll try to explain this the way I understand it. Usually to factor you have to find 2 numbers that multiply to equal the last number, and add up to equal the number part of the middle. I'll just use \[ax ^{2}+bx+c\] as an example equation. So you have to find 2 numbers that multiply to get c, and add up to get b. Then you would usually take those 2 numbers and use it to factor and get (x+?)(x+?). But since there is a number for a that is not 1 in your equation, it's a little different. First, multiply the first and last numbers 4 and -5 (a and c in the example equation). You get -20. So try to find 2 number that are factors of -20 and add up to equal 8. Just start to list the factors off on paper or in your head. Remember to include the negatives. -1, 20 1, -20 -2, 10 2, -10 These add up to equal -8 Then put 2 and -10 to separate the middle part of the equation. \[4x ^{2}+2x-10x-5\]Then group the equation into 2 separate parts. \[(4x ^{2}+2x)+(-10x-5)\]Then you take out any common factors from the parentheses.\[2x(2x+1)-5(2x+1)\]And then group together the parts you took out, which are the 2x and -5.\[(2x-5)(2x+1)\]It becomes this because 2x+1 are the same. There's your answer. Hope this helps!

  36. precal
    • 3 years ago
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    yes rose is showing the method known as factor by grouping. Both methods are correct

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