1. (2x-1)^2=16
x1=-3/2
x2=5/2
2. (7x-2)^2-4=0
49x^2-28x+4-4=0
7x(7x-4)=0
x(7x-4)=0
x1=0
7x-4=0
x2=4/7
3. 25-(5x+1)^2=0
-(5x+1)^2=-25
(5x+1)^2=25
5x+1=5
x1=-6/5
x2=4/5
4. 1.21-(2x-1)^2=0
121/100-(2x-1)^2=0
-(2x-1)^2=-121/100
(2x-1)^2=121/100
2x-1=+-11/10
2x-1=-11/10
2x-1=11/10
x1=-1/20
x2=21/20