Question

Plss giúp tôi vớiii !

(a+b)² - (a-b).(a+b)

Answer 1

=(a+b)(a+b-a+b)

=(a+b)*2b

=2b(a+b)

Answer 2

\(\left(a+b\right)^2-\left(a+b\right)\left(a-b\right)\)

\(=\left(a+b\right)\cdot\left(a+b\right)-\left(a-b\right)\cdot\left(a+b\right)\)

\(=\left(a+b\right)\cdot\left[\left(a+b\right)-\left(a-b\right)\right]\)

\(=\left(a+b\right)\left(a+b-a+b\right)\)

\(=2b\cdot\left(a+b\right)\)