TH1: x\(\ge4\)Ta có
/x+1/+/x-4/+/x+2/=4x-16
<=> x+1+x-4+x+2=4x-16
<=>3x+(1+2-4)=4x-16
<=>3x+(-1)=4x-16
<=>-1+16=4x-3x
<=>15=x
<=>x=15
Vậy x=15
Th2 x<4Ta có
/x+1/+/x-4/+/x+2/=4x-16
<=> x+1+[-(x-4)+x+2=4x-16
<=>x+1-x+4+x+2=4x-16
<=>(x-x+x)+(1+4+2)=4x-16
<=>x+7=4x-16
<=>7+16=4x-x
<=>23=3x
<=>3x=23
<=>\(x\in\varnothing\)vì 23\(⋮3̸\)
Vậy để /x+1/+/x+4/+/x+2/=4x-16 thì x = 15