Question

rút gọn các câu sau

\(\left(2x+3\right)^2+\left(2x-3\right)^2-2\left(4^2-9\right)\)

b) \(\left(x+2\right)^3+\left(x-2\right)^3+x^3-3x\left(x+2\right)\left(x-2\right)\)

Answer 1

a , \(\left(2x+3\right)^2+\left(2x-3\right)^2-2\left(4^2-9\right)=4x^2+12x+9+4x^2-12x+9-14=8x^2-4\)

Answer 2

a: Sửa đề: \(\left(2x+3\right)^2+\left(2x-3\right)^2-2\left(4x^2-9\right)\)

\(=4x^2+12x+9+4x^2-12x+9-8x^2+18\)

=36

b: \(=x^3+6x^2+12x+8+x^3-6x^2+12x-8+x^3-3x\left(x^2-4\right)\)

\(=3x^3+24x-3x^3+12x=36x\)