\(a^2+2ab+b^2-2a-2b\)
\(=\left(a^2+2ab+b^2\right)-\left(2a+2b\right)\)
\(=\left(a+b\right)^2-2\left(a+b\right)\)
\(=\left(a+b\right)\left(a+b-2\right)\)
Giải
a2 + 2ab + b2 -2a -2b
=(a2 +2ab + b2 ) +(-2a - 2b)
=(a2 +2*a*b +b2) - (2a + 2b)
=(a+b)2 - 2(a +b)
=(a +b)(a+b-2)
Study well !