Question

Solve the equation by using the quadratic formula. 8x2 – 2x - 15 =0

Answer 1

Answer:

x = 3/2 or x = -5/4

Step-by-step explanation:

Solve for x over the real numbers:

8 x^2 - 2 x - 15 = 0

Using the quadratic formula, solve for x.

x = (2 ± sqrt((-2)^2 - 4×8 (-15)))/(2×8) = (2 ± sqrt(4 + 480))/16 = (2 ± sqrt(484))/16:

x = (2 + sqrt(484))/16 or x = (2 - sqrt(484))/16

Simplify radicals.

sqrt(484) = sqrt(4×121) = sqrt(2^2×11^2) = 2×11 = 22:

x = (2 + 22)/16 or x = (2 - 22)/16

Evaluate (2 + 22)/16.

(2 + 22)/16 = 24/16 = 3/2:

x = 3/2 or x = (2 - 22)/16

Evaluate (2 - 22)/16.

(2 - 22)/16 = -20/16 = -5/4:

Answer: x = 3/2 or x = -5/4