Question

Rút gọn biểu thức:

(x+y-7)^2 -2(x+y-7)(y-6)+(y-6)^2

 

Answer 1

\(\left(x+y-7\right)^2-2\left(x+y-7\right)\left(y-6\right)+\left(y-6\right)^2\)

\(=\left(x+y-7-y+6\right)^2\)

\(=\left(x-1\right)^2=x^2-2x+1\)