Question

12．把$\underset{\underbrace{\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+…+\frac{1}{5}}}{a個(gè)}$改寫(xiě)成乘法算式是$\frac{1}{5}$×a，當(dāng)a=35時(shí)，算式的結(jié)果是7．

Answer 1

分析 $\underset{\underbrace{\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+…+\frac{1}{5}}}{a個(gè)}$表示a個(gè)$\frac{1}{5}$相加的和是多少，即$\frac{1}{5}$×a；
當(dāng)a=35時(shí)，代入$\frac{1}{5}$×a求出結(jié)果即可．

解答 解：$\underset{\underbrace{\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+\frac{1}{5}+…+\frac{1}{5}}}{a個(gè)}$=$\frac{1}{5}$×a；
a=35時(shí)，代入$\frac{1}{5}$×a可得：$\frac{1}{5}$×a=$\frac{1}{5}$×35=7．
故答案為：$\frac{1}{5}$×a，7．

點(diǎn)評(píng) 分?jǐn)?shù)乘整數(shù)的意義，與整數(shù)乘法的意義相同，表示求幾個(gè)相同加數(shù)的和是多少．