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How do you solve $x^{2} - x - 2 = 0$ $x^2 - x - 2 = 0$ by factoring?

1 Answer

Aug 12, 2015

$x = 2$ $x = 2$
or
$x = - 1$ $x = -1$

Explanation:

$x^{2} - x - 2 = 0$ $x^2-x-2 = 0$
can be factored as
$XXXX$ $color(white)("XXXX")$ $(x - 2) (x + 1) = 0$ $(x-2)(x+1)=0$

Since $a \times b = 0$ $a xx b = 0$ implies either $a = 0$ $a=0$ or $b = 0$ $b=0$

$(x - 2) \times (x + 1) = 0$ $(x-2) xx (x+1) = 0$ implies $x - 2 = 0$ $x-2 = 0$ or $x + 1 = 0$ $x+1=0$

which, in turn implies:
$XXXX$ $color(white)("XXXX")$ $x = 2$ $x=2$ or $x = - 1$ $x=-1$

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