X/2+2.1大于等于1/5(0.4-X/2)-1/4

问题描述:

X/2+2.1大于等于1/5(0.4-X/2)-1/4

X/2+2.1大于等于1/5(0.4-X/2)-1/4
=5x+21≥0.8-x-5/2
=6x≥22.7
x≥227/60