Question 645048
4x^3 - 20x^2- 25x + 125 =0

4x^2(x-5) +5^2 (-x+5) =0

(x-5)(4x^2-25) =0

x-5= 0

4x^2-25=0

x=5

4x^2 = 25

x^2=5^2/2^2    

x=5/2

(x^2)1/2 = -(5^2/2^2)^1/2

x= -(5^2)^1/2/ (2^2)^1/2

x= -5/2

x 5, 5/2, -5/2