Question

Tích (2 . x²ⁿ + 3 . x^2n-1)(x^1-2n - 3 . x^2-2n) là ....

Answer 1

Answer 2

\(\left(2.x^{2n}+3.x^{2n-1}\right)\left(x^{1-2n}-3.x^{2-2n}\right)\)

\(=\left(2x^{2n}.x^{1-2n}-2x^{2n}.3x^{2-2n}\right)+\left(3x^{2n-1}.x^{1-2n}-3x^{2n-1}.3x^{2-2n}\right)\)

\(=\left(2x^{2n+1-2n}-6x^{2n+2-2n}\right)+\left(3x^{2n-1+1-2n}-9x^{2n-1+2-2n}\right)\)

\(=\left(2x-6x^2\right)+\left(3x^0-9x\right)\)

\(=2x-6x^2+3-9x\)

\(=-6x^2-7x+3\)