Question

18．下列關(guān)于單項(xiàng)式-$\frac{{4x{y^2}}}{5}$的說法中，正確的是（　�。�

• A． 系數(shù)是$-\frac{4}{5}$，次數(shù)是2
• B． 系數(shù)是$\frac{4}{5}$，次數(shù)是2
• C． 系數(shù)是-4，次數(shù)是3
• D． 系數(shù)是$-\frac{4}{5}$，次數(shù)是3

Answer 1

分析 根據(jù)單項(xiàng)式系數(shù)、次數(shù)的定義來求解．單項(xiàng)式中數(shù)字因數(shù)叫做單項(xiàng)式的系數(shù)，所有字母的指數(shù)和叫做這個單項(xiàng)式的次數(shù)．

解答 解：根據(jù)單項(xiàng)式系數(shù)、次數(shù)的定義可知，單項(xiàng)式-$\frac{{4x{y^2}}}{5}$的系數(shù)是：-$\frac{4}{5}$，次數(shù)是：1+2=3．
故選：D．

點(diǎn)評 此題主要考查了單項(xiàng)式，確定單項(xiàng)式的系數(shù)和次數(shù)時，把一個單項(xiàng)式分解成數(shù)字因數(shù)和字母因式的積，是找準(zhǔn)單項(xiàng)式的系數(shù)和次數(shù)的關(guān)鍵．