Verified answer

1) (x-3)(x+3)=0

x1= 3; x2= -3

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

x1= 4; x2= -4

3) (5-2x)(5+2x)=0

x1= 2,5; x2= -2,5

4) (7x-4)(7x+4)= 0

x1= 4/7; x2= -4/7