Answer:
x = - 3, x = 0.5
Explanation:
Given
10x² + 5x - 15 = - 12 + 8x² ( subtract 8x² from both sides )
2x² + 5x - 15 = - 12 ( add 12 to both sides )
2x² + 5x - 3 = 0 ← in standard form
(x + 3)(2x - 1) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 3 = 0 ⇒ x = - 3
2x - 1 = 0 ⇒ 2x = 1 ⇒ x = 0.5