Question

X^2+3=180

solve for x.

a. -18 and 10
b. -15 and 12
c. -12 and 15
d -10 and 18

Answer 1

b

Explanation:

x² + 3x = 180

x² + 3x - 180 = 0

Sum = 3

Product = -180

Factors = 15 , -12 {15 *(-12) = -180 & 15 + (-12) = 3 }

x² + 15x -12x - 180 = 0

x² + 15x - 12x - 12*15 = 0

x(x + 15) - 12(x + 15) = 0

(x +15)(x - 12) = 0

x + 15 = 0 ; x -12 = 0

x= -15 ; x = 12