Answer:
x = ± 
Step-by-step explanation:
Given
25x² + 1 = 10 ← subtract 10 from both sides
25x² - 9 = 0 ← in standard form
note that 25x² - 9 is a difference of squares and factors as
(5x - 3)(5x + 3) = 0
Equate each factor to zero and solve for x
5x - 3 = 0 ⇒ 5x = 3 ⇒ x = 
5x + 3 = 0 ⇒ 5x = - 3 ⇒ x = - 