a. x^2=144 ; x^2-144=0 ; x=12, x=-12
b. x^2=256 ; x^2-256=0; x=16, x=-16
c. x^2=400 ; x^2-400=0; x=20, x=-20
d. x^2=576 ; x^2-576=0; x=24, x=-24
e. x^2=625 ; x^2-625=0 ; x=25, x=-25
f. 3x^2=300 ; 3x^2-300=0; x=-10, x=10
g. 4x^2=324 ; 4x^2-324=0; x=-9, x=9
h. 7x^2=6300 ; 7x^2-6300=0; x=-30, x=30
