Answer:
x = 3 or x = -3
Step-by-step explanation:
Solve for x over the real numbers:
2 x (x + 3) - 6 (x + 3) = 0
Expand out terms of the left hand side:
2 x^2 - 18 = 0
2 x^2 - 18 = 2 (x^2 - 9):
2 (x^2 - 9) = 0
Divide both sides by 2:
x^2 - 9 = 0
x = (0 ± sqrt(0^2 - 4 (-9)))/2 = ( ± sqrt(36))/2:
x = sqrt(36)/2 or x = (-sqrt(36))/2
sqrt(36) = sqrt(4×9) = sqrt(2^2×3^2) = 2×3 = 6:
x = 6/2 or x = (-6)/2
6/2 = 3:
x = 3 or x = (-6)/2
(-6)/2 = -3:
Answer: x = 3 or x = -3
