How do you solve x/(x-1)>2xx1>2?

1 Answer
Jun 19, 2018

The solution is x in (2,4)x(2,4)

Explanation:

You cannot do crossing over.

The inequality is

x/(x-2)>2xx2>2

=>, x/(x-2)-2>0xx22>0

Placing on the same denominator

=>, (x-2(x-2))/(x-2)>0x2(x2)x2>0

=>, (x-2x+4)/(x-2)>0x2x+4x2>0

=>, (4-x)/(x-2)>04xx2>0

Let f(x)=(4-x)/(x-2)f(x)=4xx2

Let's build a sign chart

color(white)(aaaa)aaaaxxcolor(white)(aaaa)aaaa-oocolor(white)(aaaaaa)aaaaaa22color(white)(aaaaaa)aaaaaa44color(white)(aaaa)aaaa+oo+

color(white)(aaaa)aaaax-2x2color(white)(aaaaaa)aaaaaa-color(white)(aa)aa||color(white)(aa)aa++color(white)(aaaa)aaaa++

color(white)(aaaa)aaaa4-x4xcolor(white)(aaaaaa)aaaaaa++color(white)(aaaa)aaaa#color(white)(a)+#color(white)(aaaa)aaaa-

color(white)(aaaa)aaaaf(x)f(x)color(white)(aaaaaaa)aaaaaaa-color(white)(aaaa)aaaa#color(white)(a)+#color(white)(aaaa)aaaa-

Therefore,

f(x)>0f(x)>0 when x in (2,4)x(2,4)

graph{(4-x)/(x-2) [-20.27, 20.27, -10.14, 10.14]}