The square of a number plus the number is 12. What is the number?

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Answer 1 · 2016-12-11T00:16:10

$x = -4$ or $x = 3$

If $x$ represents the number, then we can express the given information as:

$x^2+x=12$

Subtract $12$ from both sides to get a quadratic equation in standard form:

$x^2+x-12 = 0$

Note that $4*3 = 12$ and $4-3 = 1$ . So we find:

$(x+4)(x-3) = x^2+x-12 = 0$

Hence $x = -4$ or $x = 3$