(A+2B)^2=?A-2B=7,AB=3
问题描述:
(A+2B)^2=?A-2B=7,AB=3
答
A-2B=7,AB=3
(A+2B)^2=A^2+4AB+4B^2=(A^2-4AB+4B^2)+8AB=(A-2B)^2+8AB
=7^2+8*3=73