数学计算题;(-0.5)+(9/2)+(-19/2)+9.75=?(-1/2)+(-2/5)+(3/2)+(18/5)+(39/5)=?
问题描述:
数学计算题;(-0.5)+(9/2)+(-19/2)+9.75=?(-1/2)+(-2/5)+(3/2)+(18/5)+(39/5)=?
答
=(-1/2)+(9/2)-(9又1/2)+(9又3/4)
=(9/2)-(1/2)-9+9+(3/4-2/4)
=4+1/4
=4又1/4
=3/2-1/2+18/5+39/5-2/5
=1+(18+39-2)/5
=1+11
=12