Question

Which values of x make this equation true?

x²+x=12
f. - 6 and 2
h. - 3 and 4
g. -4 and 3
j. - 2 and 6

Answer 1

`{x}^(2) + x = 12 \\ {x}^(2) + x - 12 = 0 \\ {x }^(2) + 4x - 3x - 12 = 0 \\ x(x + 4) - 3(x + 4) = 0 \\ (x + 4)(x - 3) = 0 \\ either \: \: \: or \: \\ x = - 4 \: \: \: \: \: \: \: \: \: \: \: \: x = 3`

the answer is -4 and 3