Question

Answer 1

i: Ta có: \(\left(3x-4\right)^2+2\left(3x-4\right)\left(4-x\right)+\left(4-x\right)^2\)

\(=\left(3x-4+4-x\right)^2\)

\(=4x^2\)

j: Ta có: \(\left(3a-1\right)^2+2\left(9a^2-1\right)+\left(3a+1\right)^2\)

\(=\left(3a-1+3a+1\right)^2\)

\(=36a^2\)