Answer:
15 or -5
Step-by-step explanation:
√(25-40x)= x-10
Squaring both sides
25 - 40x = (x -10)²
25 - 40x = x² -20x + 100
x² - 20x + 40x + 100 - 25 =0
x² +20x = -75
x² + 20x + 10² = -75 + 100
(x + 10)² = 25
x - 10 = ±√25
x - 10 = ±5
x = ±5 + 10
x = 15 or x = -5
