Question

Factorise and find the value of the following
x power 2-4ypower 2, when x= 4, y=2

Answer 1

x²-4y²
⇒4²-16
⇒16-16
∴0

Answer 2

i)x^2- (2y)^2
=(x+2y)(x-2y) here we used a^2-b^2=(a+b)(a-b)
ii) if x=4, y=2
Value of x^2 -(2y)^2
=4^2-(2*2)^2
=16 - 16
=0