Question

Rút gọn biểu thức 

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

Answer 1

\(=\left(18x^{2n-3}+3x^n\right)-\left(18x^{2n-3}-2x^n\right)\)
\(=18x^{2n-3}+3x^n-18x^{2n-3}+2x^n\)
\(=\left(18x^{2n-3}-18x^{2n-3}\right)+\left(3x^n+2x^n\right)\)
\(=5x^n\)

Answer 2

\(=18x^{2n-3}+3x^n-18x^{2n-3}+2x^n=5x^n\)