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anonymous

  • 5 years ago

Does anyone know how to factor trinomials completely? I need to factor: 20a - 2a^ - 18 completely. Here is what I have so far: 2(10A - a^ -9). What do I do next? The solution is: -2(a - 9)(a - 1) but I cannot figure out how to get there.

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  1. anonymous
    • 5 years ago
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    you need to put the a^2 term first

  2. anonymous
    • 5 years ago
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    Use reverse FOIL?

  3. anonymous
    • 5 years ago
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    I understand I need to put the a ^ 2 first, but I don't understand WHY I need too?? How do you know to put the a ^2 first?

  4. anonymous
    • 5 years ago
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    -2a^2 + 20a - 18 factor out a -2 -2(a^2 - 10a + 9) you need factors of 9 that add to get 10 ---- 9 and 1 -2(a - 9)(a - 1)

  5. anonymous
    • 5 years ago
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    -2(a^2-10a+9)=0 (a-9)(a-1)=0 a=1,9

  6. anonymous
    • 5 years ago
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    the form of a quadratic is ax2+bx+c

  7. anonymous
    • 5 years ago
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    great ankur!

  8. anonymous
    • 5 years ago
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    thanx

  9. anonymous
    • 5 years ago
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    Think about... what 2 numbers times each other equals -9 and added together equals -10.. Also always make sure the a^2 term is positive so it will make the factoring very easy

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