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AshhSmith

  • 2 years ago

a^2 – a – 20 factor completely

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  1. vishweshshrimali5
    • 2 years ago
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    \[a^2 - a - 20 = a^2 - 5a + 4a - 20\] Now u can simplify this

  2. agentx5
    • 2 years ago
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    Hint: -5 and +4 ;-) Got it now?

  3. Callisto
    • 2 years ago
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    From @vishweshshrimali5 's work: a^2 - a - 20 = a^2 - 5a + 4a - 20 = a (a-5) + 4(a-5) = (a+4)(a-5) If you have to solve the quad. equation, that's another case.

  4. agentx5
    • 2 years ago
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    a^2-a-20=(a-5)(a+4) I stand by what I said. -5 + 4 = -1 -5 * 4 = -20

  5. agentx5
    • 2 years ago
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    So no, not wrong answer. Dude.

  6. AshhSmith
    • 2 years ago
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    thank you guys

  7. Callisto
    • 2 years ago
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    Sorry @vishweshshrimali5 I think you're more like solving the quadratic equation than just factor the expression. Please look at the question again

  8. vishweshshrimali5
    • 2 years ago
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    @Callisto very correct I regret for my mistake We just had to factorise right ?

  9. Callisto
    • 2 years ago
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    Root is negative of the number in the factor. I'm 100% sure that @agentx5 is correct!

  10. agentx5
    • 2 years ago
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    I'm not using the quadratic. I'm doing it in my head by considering what would have to come back together to for a^2-a-20 when I F.O.I.L. the factors together.

  11. Callisto
    • 2 years ago
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    Yes @vishweshshrimali5

  12. Callisto
    • 2 years ago
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    @vishweshshrimali5 You shouldn't be sorry. Instead we are so sorry to tell you that the question is *factor completely*

  13. agentx5
    • 2 years ago
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    Neither Callisto nor I have forgotten, this is just a method that works easier and faster in this situation as a method to factor, and just as correct. Roots implies an EQUATION, not an EXPRESSION.

  14. agentx5
    • 2 years ago
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    There is no '=' in the original question.

  15. Callisto
    • 2 years ago
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    @vishweshshrimali5 No. If it is the quadratic equation. It is solve like this: a^2 – a – 20 =0 (a-5)(a+4) =0 a-5 =0 or a+4 =0 a=5 or a=-4

  16. Callisto
    • 2 years ago
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    @vishweshshrimali5 I've posted the way to do it

  17. AshhSmith
    • 2 years ago
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    can you factor a^2 – 5a – 20 out for me ?

  18. vishweshshrimali5
    • 2 years ago
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    @Callisto I think I have misunderstood u all Sorry for that

  19. vishweshshrimali5
    • 2 years ago
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    What @agentx5 was saying were not roots right ? u were telling how to write -x = -5x + 4x right ? Sorry everyone I regret for my words

  20. Callisto
    • 2 years ago
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    It's okay. Is that clear to you now? @vishweshshrimali5

  21. agentx5
    • 2 years ago
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    But then again there was NO f(a)=0 equation, it was simply an expression. @AshhSmith , Callisto and I both did that (see above) :-)

  22. vishweshshrimali5
    • 2 years ago
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    If I m not wrong @Callisto told the way to factorise @agentx5 told how to write -x = -5x + 4x and I told how to solve the quadratic eq. Sorry everyone Please don't mind that

  23. Callisto
    • 2 years ago
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    @AshhSmith First, please post it as a new question. Second, I'm sure we're all glad to help, provided that you've tried to work out the answer first - no matter you succeed or not. Third, in response to your question, if you need to form (ax+b)(cx+d) where a, b, c, and d are integers, then it can't be factored in the case x^2-5x-20.

  24. Callisto
    • 2 years ago
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    @vishweshshrimali5 I hope I can explain it clearly to you... First it's about 'factor completely' Factor completely is about factoring the expression. The expression given in the question is x^2 -x - 20 So, we have to factor it. x^2 - x -20 = x^2 - 5x + 4x - 20 = x (x-5) + 4(x-5) = (x-5)(x+4) This is what factor completely is, and nothing more. What you've been talking about is solve the equation. And the way you've been working is to use some properties of quadratic equation to work out the roots ( that is the value of the unknowns) of the quadratic equation. With the word ''equation'', that means there are TWO sides and a equal sign in between (that is '=') and you need to SOLVE it. For example : x^2 -x - 20 = 0 -> you can see there are TWO sides separated by an equal sign. To solve it. One of the techniques is to factor it. That is x^2 -x - 20 = 0 (x-5)(x+4) = 0 Since two factors multiply to give 0, one of them must be 0. So, (x-5) =0 or (x+4) =0 x = 5 or x = -4 This is solving the equation/ solve x/ find the roots of the equation, but NOT factor the expression. I hope it's clearer to you now.

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