Question

17．已知單項(xiàng)式-x^m-2y³與$\frac{2}{3}$xⁿy^2m-3n是同類項(xiàng)，那么m，n的值分別是（　�。�

• A． $\left\{\begin{array}{l}{m=3}\\{n=-1}\end{array}\right.$
• B． $\left\{\begin{array}{l}{m=3}\\{n=1}\end{array}\right.$
• C． $\left\{\begin{array}{l}{m=-3}\\{n=1}\end{array}\right.$
• D． $\left\{\begin{array}{l}{m=-3}\\{n=-1}\end{array}\right.$

Answer 1

分析 根據(jù)同類項(xiàng)的定義列出二元一次方程組，然后求解即可．

解答 解：∵單項(xiàng)式-x^m-2y³與$\frac{2}{3}$xⁿy^2m-3n是同類項(xiàng)，
∴$\left\{\begin{array}{l}{m-2=n}\\{2m-3n=3}\end{array}\right.$，
解得$\left\{\begin{array}{l}{m=3}\\{n=1}\end{array}\right.$．
故選B．

點(diǎn)評 本題考查了同類項(xiàng)，所含字母相同，并且相同字母的指數(shù)也分別相同的項(xiàng)叫做同類項(xiàng)．