Question

expand (2x-y+x)^2 using suitable method

Answer 1

Identity to be used

• $\sf{(a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)}$

Now, from the structure

($\sf{a=2x}$, $\sf{b=-y}$, $\sf{c=z}$)

→ $\sf{(2x-y+z)^2=(2x)^2+(-y)^2+z^2+2((2x)(-y)+(-y)(z)+(z)(2x))}$

→ $\sf{(2x-y+z)^2=4x^2+y^2+z^2+2(-2xy-yz+2zx)}$

$\sf{}\therefore}{(2x-y+z)^2=4x^2+y^2+z^2+-4xy-2yz+4zx}$