Question

rút gọn: \(\left(2a-5b\right)^2+\left(2a+5b\right)^2\)

giúp mk với ạ, tks các bn nhiều

Answer 1

\(\left(2a-5b\right)^2+\left(2a+5b\right)^2\)

\(=\left(2a\right)^2-2\cdot2a\cdot5b+\left(5b\right)^2+\left(2a\right)^2+2\cdot2a\cdot5b+\left(5b\right)^2\)

\(=2\cdot\left[\left(2a\right)^2+\left(5b\right)^2\right]\)

\(=2\left(4a^2+25b^2\right)=8a^2+50b^2\)

Answer 2

\(\left(2a-5b\right)^2+\left(2a+5b\right)^2=2\left[\left(2a\right)^2+\left(5b\right)^2\right]=2\cdot4a^2+2\cdot25b^2=8a^2+50b^2\)

Answer 3

(2a-5b)² +(2a+5b)²

= (2a-5b)² -(-2a-5b)²

⁼ (2a-5b-2a-5b)(2a-5b+2a+5b)

= (-10b)(4a)

= -40ab