y=3√x-5-2/5√5-x+2求4x+8y

问题描述:

y=3√x-5-2/5√5-x+2求4x+8y

要使根号内的数有意义,
必须:x-5=5-x=0
解得:x=5
则:y=2
4x+8y=20+16=36