Question

Expand : [2x − 7y + z]square
using appropriate identity

Answer 1

(2x-7y)^2=(2x)^2+(7y)^2-2 (2x)(7y)

=4x^2+49y^2-28xy

Identity->(a-b)^2=a^2+b^2-2ab

Answer 2

Step-by-step explanation:

given

[2x − 7y + z]^2

using identity (a+b+c)^2 = (a)^2+(b)^2+(c)^2+2ab+2bc+2ca

so

[2x − 7y + z]^2 = (2x)^2+(-7y)^2+(z)^2+2×2x×(-7y)+2(-7y)z+2z×2x

= 2x^2+49y^2+z^2-28xy-14yz+4zx