Question

m为何值时,代数式2m-(5m-1)/3的值与代数式(7-m)/2的值互为相反数?

Answer 1

互为相反数的两个数之和为0,所以

[2m-(5m-1)/3]+[(7-m)/2]=0

2m-(5m-1)/3+(7-m)/2=0

12m-2(5m-1)+3(7-m)

12m-10m+2+21-3m=0

-m+23=0

m=23