2x² = 72
x² = 72/2 = 36
x = + 6 or -6
t² + 12t + 36 = 0 by factoring
( t + 6) (t+ 6) = 0
t = -6
w² - 64 = 0 ^ w² = 64 ^ w = + 6 or -6 by square root method
example of a quadratic equation that cannot be solved by factoring
x² + 4x + 5= 0 because the factor of 5 is 1 & 5, when you add 1 + 5 =6
it must be 4 before it can be solved by factoring
so you must solve by formula or completing the square method