4(x+3y)^2+1-4(x+3y)=( )^2

问题描述:

4(x+3y)^2+1-4(x+3y)=( )^2

4(x+3y)^2+1-4(x+3y)
=4(x+3y)^2-4(x+3y)+1
=[2(x+3y)-1]^2
=(2x+6y-1)^2