數學題之53 用遞等式計算. 1.15/4*12/5-12/5/120% 2.100.1-(2.625+0.425)*30 3.99/{23/4-(9/5+21/5*2/7)} 4.(1/4+3/8)/(1-3/10)

數學題之53 用遞等式計算. 1.15/4*12/5-12/5/120% 2.100.1-(2.625+0.425)*30 3.99/{23/4-(9/5+21/5*2/7)} 4.(1/4+3/8)/(1-3/10)


用遞等式計算.1.15/4*12/5-12/5/120% =9-2 =7 2.100.1-(2.625+0.425)*30 =100.1-3.05*30 =100.1-91.5 =8.6 3.99/{23/4-(9/5+21/5*2/7)} =99/[23/4-3] =99/11/4] =36 4.(1/4+3/8)/(1-3/10)=5/8/(7/10)=25/2…



一根木頭鋸成4段要9分鐘,如果鋸成6段要______分鐘.


4-1=3(次),9÷3=3(分鐘),6-1=5(次),3×5=15(分鐘),答:如果鋸6段需15分鐘.故答案為:15.