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How do I factor this equation?

2x^2+9x-11=0

I know the answer is (2x+11)(x-1)=0, but I do not understand how you get that answer. Someone please explain.

2 Antworten

Relevanz
  • vor 8 Jahren

    Factoring is using just rewriting the equation so (2x+11)(x-1)=2x^2+9x-11 kind of like saying x-2=-2+x

    If you expand (2x+11)(x-1) by multiplying them out like so 2x*x+2x*-1+11*x+11*-1 you get 2x^2-2x+11x-11=2x^2+9x-11

    Factoring is always for an equation with x^2 written as (ax+/-b)(cx+/-d) where ax*cx must equal the original ?x^2 in this case 2x^2 and b*d must equal the number without any variable(or an x) in this case -11 [make sure the sign +/- is correct so for a negative either b or d is positive and the other negative since a positive times a negative is a negative]

    The tricky part is that a*d+c*b= the single variable x in this case 9

    So look at 2x^2 forget the x and so what two numbers make 2 for a and c {which is 2*1 only and for a and c it doesn't matter which is 2 and which is 1} so we know this much (2x+/-b)(1x+/-d)

    Now b*d must equal -11 so the two number that make up -11 are either -1 and 11 or -11and 1 so we must figure out which is what we need by looking at how we get 9 from a*d+c*b or 2*d+1*b

    So we can plug in each option which is 4 since we have 4 possible options for d [1,-1,11,-11] now try them and their counterpart for b {for 1 it's -11, for -1 it's 11...}

    We get d=-1 and b=11

    So now put those in the (ax+/-b)(cx+/-d) so (2x+11)(x-1) and that's how you factor

    Sorry tried to make it as simple as possible just in case

    Good luck and God Bless

  • vor 8 Jahren

    2x^2 +9x -11 = 0

    COEFFICIENT OF x^2 = +2

    ( +2) ( -11) = -22

    FIND FACTORS OF -22 WHICH ADD UP TO +9 ( COEFFICIENT OF x )

    ( -2) (+11) = -22

    2x^2 -2x +11x -11 = 0

    2x ( x-1) +11( x-1) = 0

    ( 2x +11) ( x-1) = 0

    x = 1 OR -11/2 ANSWER

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