Question

Nine times a certain number is 5 less than twice the square of the number

Answer 1

Explanation:

9·x = 2·x^2 - 5

2·x^2 - 9·x - 5 = 0

x^2 - 9/2·x - 5/2 = 0

x = 9/4 ± √(81/16 + 40/16) = 9/4 ± √(121/16) = 9/4 ± 11/4

x1 = -1/2 = -0.5 or x2 = 5

Answer 2

-1/2 or 5

Explanation:

9n = (2 * n^2) - 5 => n = -0.5 and n = 5