7.2+(-1.8)-(-0.8) (写出过程) 0.6-1/4-(-3.75)+2/5 (-2/5)+(3又4/7)-1.6-(11/7)

问题描述:

7.2+(-1.8)-(-0.8) (写出过程) 0.6-1/4-(-3.75)+2/5 (-2/5)+(3又4/7)-1.6-(11/7)

7.2+(-1.8)-(-0.8)
=7.2-1.8+0.8
=7.2-(1.8-0.8)
=7.2-1
=6.2

0.6-1/4-(-3.75)+2/5
=0.6-0.25+3.75+0.4
=(0.6+0.4)+(3.75-0.25)
=1+3.5
=4.5

(-2/5)+(3又4/7)-1.6-(11/7)
=-(0.4+1.6)+(3又1/7-1又1/7)
=-2+2
=0