Question

Solve x = √2x + 15.

Do not include extraneous solutions.
X = = [?]
The whole 2x+15 is under the square root sign

Answer 1

x = 5

Explanation:

2x + 15 ≥ 0

2x ≥ -15

x ≥ -15/2

x ≥ 0

the expression has meaning only if x ≥ 0

`x^2 = √(2x+15)^2`

x² = 2x + 15

x² - 2x -15 = 0

(x-5)(x+3) = 0

x = 5

x = -3 (not acceptable)