若X是方程2X-M/4-1/2=X-M/3的解,求代数式1/4(-4M^2+2M-8)-(1/2M-1)的值
问题描述:
若X是方程2X-M/4-1/2=X-M/3的解,求代数式1/4(-4M^2+2M-8)-(1/2M-1)的值
若X=1/2m 是方程2x-m/4-1/2=x-m/3的解,求代数式1/4(-4mm+2m-8)-(1/2m-1)的值
答
将x=1/2m代入方程得:
m-1/4m-1/2=1/2m-1/3m
(1-1/4-1/2+1/3)m=1/2
7/12m=1/2
m=6/7
1/4(-4mm+2m-8)-(1/2m-1)
=-mm+1/2m-2-1/2m+1
=-mm-1
=-85/49