Answer:
B) x = 3 or x = -5/2
Step-by-step explanation:
Solve for x over the real numbers:
2 x^2 - x = 15
Subtract 15 from both sides:
2 x^2 - x - 15 = 0
x = (1 ± sqrt((-1)^2 - 4×2 (-15)))/(2×2) = (1 ± sqrt(1 + 120))/4 = (1 ± sqrt(121))/4:
x = (1 + sqrt(121))/4 or x = (1 - sqrt(121))/4
sqrt(121) = sqrt(11^2) = 11:
x = (1 + 11)/4 or x = (1 - 11)/4
(1 + 11)/4 = 12/4 = 3:
x = 3 or x = (1 - 11)/4
(1 - 11)/4 = -10/4 = -5/2:
Answer: x = 3 or x = -5/2
