Answer :
Your equation: 4x² - 100 = 0
Factor the left side: (2x + 10) · (2x - 10) = 0
This equation is true if either factor is zero.
-- One factor: 2x + 10 = 0
Divide each side by 2: x + 5 = 0
Subtract 5 from each side: x = -5 .
-- The other factor: 2x - 10 = 0
Divide each side by 2: x + 5 = 0
Add 5 to each side: x = 5 .