How do you solve $x^2 – x – 2 = 0$ ?

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Answer 1 · 2015-08-01T22:31:03

Solve y = x^2 - x - 2 = 0

Answer: -1 and 2.

Since (a - b + c = 0), use the shortcut. The 2 real roots are:
-1 and (-c/a = 2/1 = 2)

REMINDER of Shortcut.

When (a + b + c = 0) --> 2 real roots -> 1 and (c/a)

When (a - b + c = 0) --> 2 real roots --> (- 1) and (- c/a).

Try to remember this Shortcut. It will save you a lot of time and effort!!!.

Answer 2 · 2015-08-02T14:25:49

$x=-1, 2$

$x^2-x-2$ is in the form of a quadratic equation, $ax+bx+c$ , where $a=1, b=-1, and c=-2$ . The quadratic formula can be used to solve this problem.

Quadratic Formula

$x=(-b+-sqrt(b^2-4ac))/(2a)$ =

$x=(-(-1)+-sqrt((-1)^2-4*1*-2))/(2*1)$ =

$x=(1+-sqrt(1+8))/2$ =

$x=(1+-sqrt9)/2$ =

$x=(1+-3)/2$

Solve for $x$ .

$x=(1+3)/2=4/2=2$

$x=(1-3)/2=-2/2=-1$

How do you solve x^2 – x – 2 = 0x^2 – x – 2 = 0?