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Shannon20150

  • 3 years ago

Factor 2x4 - 20x2 - 78. 2(x2- 3)(x2- 13) ***** 2(x2+ 3)(x2- 13) 2(x2- 3)(x2+ 13) I think is right ****

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  1. Shannon20150
    • 3 years ago
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    help me @FibonacciChick666

  2. FibonacciChick666
    • 3 years ago
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    I would like you to please first try and check your answer before I try the problem. You are going to do this by using the FOIL method.

  3. Shannon20150
    • 3 years ago
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    I did that's y I asked if its right

  4. FibonacciChick666
    • 3 years ago
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    alrighty good, I'm working on it right now

  5. Shannon20150
    • 3 years ago
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    okay lol

  6. FibonacciChick666
    • 3 years ago
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    ok so only one of your answers is correct. let's go through the process together.

  7. rosedewittbukater
    • 3 years ago
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    First factor out the 2 to get 2(x^4-10x^2-39) Replace any x^2 value with the variable a, so x^4 becomes a^2 because x^2 squared is x^4. You just do this to take the place of any x^2 s to make it easier, if that makes sense. So 2(a^2-10a-39). Then you can do regular factoring. 3 and -13 multiply to become -39, and 3-13=10. So The equation would become \[2(a+13)(a-3)\] Then change the a's back into x^2. So the answer is \[2(x ^{2}+3)(x ^{2}-13)\] So the answer is the second one.

  8. FibonacciChick666
    • 3 years ago
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    So the first thing that we want to do is pull out any like terms. What does each term in the expression have in common?

  9. Shannon20150
    • 3 years ago
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    x2

  10. Shannon20150
    • 3 years ago
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    okay I need help again

  11. FibonacciChick666
    • 3 years ago
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    ok, does the term (-78) contain an \[x ^{2}\]

  12. Shannon20150
    • 3 years ago
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    idk

  13. rosedewittbukater
    • 3 years ago
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    You can check your work by multiplying the factors back together using either the box method or FOIL. \[2(x ^{4}-13x ^{2}+3x ^{2}-39)\]Combine like terms to get \[2(x ^{4}-10x ^{2}-39)\]Then distribute the 2 \[2x ^{4}-20x ^{2}-78\]You know your answer is correct if it is the same as the original equation.

  14. Shannon20150
    • 3 years ago
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    will u help me in another problem @rosedewittbukater

  15. FibonacciChick666
    • 3 years ago
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    let's try a different approach. can you divide -78 by x^2 without leaving a remainder?

  16. Shannon20150
    • 3 years ago
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    yes

  17. rosedewittbukater
    • 3 years ago
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    Sure

  18. Shannon20150
    • 3 years ago
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    okay I posted it already

  19. FibonacciChick666
    • 3 years ago
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    ok so what is -78 divided by x^2 ?

  20. rosedewittbukater
    • 3 years ago
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    Where did you post it

  21. Shannon20150
    • 3 years ago
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    is it -39

  22. Shannon20150
    • 3 years ago
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    on open questions

  23. FibonacciChick666
    • 3 years ago
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    -39 is -78 divided by only 2 but think about the other terms listed do they also divide by 2?

  24. Shannon20150
    • 3 years ago
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    idk

  25. rosedewittbukater
    • 3 years ago
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    She's trying to ask what number or value can be divided out of every single part of the equation. There's no x^2 in 78 so the only common number that all of the numbers can be divided by is 2.

  26. FibonacciChick666
    • 3 years ago
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    let's try a slightly simplified example if you have the equation: \[2x+2\] What number is common to both terms?

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