How do you solve $x^2-x-12=0$ ?

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Answer 1 · 2015-05-19T07:58:45

We can Split the Middle Term of this equation and factorise it to find the solution.

In this technique, if we have to factorise an expression like $ax^2 +bx + c$ , we need to think of two numbers such that:

$N_1 xx N_2 = a xx c = 1 xx (-12) = -12$

and

$N_1 +N_2 = b = -1$

After trying out a few numbers we get $N_1 = -4$ and $N_2 =3$
$(-4) xx 3 = -12$ , and $(-4) + 3= -1$

$x^2 -x -12 = x^2 -4x +3x -12$
$= x(x-4)+3 (x-4)$
$= (x+3)(x-4)$

the solution is $color(blue)x=-3 , color(blue)x=4$

How do you solve x^2-x-12=0x^2-x-12=0?