Answer :
I hope this helps you
(square root of 16x^2)^2=(56x)^2
16x^2=56^2.x^2
64.49x^2-16x^2=0
16x^2 (49.4-1)=0
16x^2.165=0
x=0
(square root of 16x^2)^2=(56x)^2
16x^2=56^2.x^2
64.49x^2-16x^2=0
16x^2 (49.4-1)=0
16x^2.165=0
x=0