SOLUTION: Factor completely. x^2 - 13x + 36 I get (x - 9) (x-4) by looking at it - but to break it down I am not sure how to get to this answer. Thanks

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Factor completely. x^2 - 13x + 36 I get (x - 9) (x-4) by looking at it - but to break it down I am not sure how to get to this answer. Thanks      Log On


   

Question 41570: Factor completely.
x^2 - 13x + 36
I get (x - 9) (x-4) by looking at it - but to break it down I am not sure how to get to this answer.
Thanks
Answer by mszlmb(115) About Me  (Show Source):
You can put this solution on YOUR website!
x^2 - 13x + 36



what two numbers add up to -13 and multiply to 36?

We know they are both negative for producing a positive product and a negative sum.

36=18*2=9*4 aha! sum of 13!

so..

x2-9x-4x+36  factor like terms

x(x-9)-4(x-9)  put like terms together

(x-4)(x-9) ther ya go!

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