(-1/7)+(-2/5)+7/9+(+1/7)+(-3/5)簡算過程. (-1/7)+(-2/5)+7/9+(+1/7)+(-3/5)簡算過程. 3/7×(-1/5)+3/7×(-4/5)-3/7×3/10簡算過程

(-1/7)+(-2/5)+7/9+(+1/7)+(-3/5)簡算過程. (-1/7)+(-2/5)+7/9+(+1/7)+(-3/5)簡算過程. 3/7×(-1/5)+3/7×(-4/5)-3/7×3/10簡算過程


(1)原式=-1/7-2/5+7/9+1/7-3/5=7/9+(1/7-1/7)-(2/5+3/5)=7/9+0-1=-2/9(2)原式=3/7×(-1/5)+3/7×(-4/5)+3/7×(-3/10)=3/7×(-1/5-4/5-3/10)=3/7×(-1-3/10)=-3/7×13/10=-39/70