当a=3.8,b=0.4时,求1.2a一5b十0.7a一2.5b的值.
问题描述:
当a=3.8,b=0.4时,求1.2a一5b十0.7a一2.5b的值.
答
1.2*3.8-5*0.4+0.7*3.8-2.5*0.4
=4.56-2+2.66-1
=2.56+2.66-1
=4.22