a)3x²=27 =>x²=9 =>x=3 sau x=(-3)
b)2x²=72 =>x²=36 =>x=6 sau x=(-6)
c)5x²=720 =>x²=144 =>x=12 sau x=(-12)
d)-4x²=-36 =>x²=9 =>x=3 sau x=(-3)
e)0,2x²=7,2 =>x²=36 =>x=6 sau x=(-6)
f)0,2x²=5/18 =>x²=5/18 : 1/5 =>x²=25/18 =>x=5/3√2=5√2/6 sau x=(-5√2/6)
g)169x²=9 =>x²=9/169 =>x=3/13 sau x=(-3/13)
h)√2x²=√50 =>√2x²=5√2 =>x²=5 =>x=√5 sau x=(-√5)