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

Question

8445 views around the world

You can reuse this answer
Creative Commons License

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#