Question

Cuanto es (x-2)²-25=0

Answer 1

(x-2)² -25 = 0 
x² -4x +4 -25 = 0 -------> x² -4x -21 = 0

Fórmula general:
                     ________
            –b ± √ b² – 4ac
x₁, x₂ = ———————
                     2a

a = 1
b = -4
c = -21

x₁ = (4+10) / 2 = 7
x₂ = (4-10) / 2 = -3

Saludos.