How do you solve (3x+2)/(x-4)<03x+2x4<0?

1 Answer
Jun 6, 2017

The solution is x in (-2/3,4)x(23,4)

Explanation:

Let f(x)=(3x+2)/(x-4)f(x)=3x+2x4

We build a sign chart

color(white)(aaaa)aaaaxxcolor(white)(aaaa)aaaa-oocolor(white)(aaaa)aaaa-2/323color(white)(aaaaaaa)aaaaaaa44color(white)(aaaaaaaa)aaaaaaaa+oo+

color(white)(aaaa)aaaa3x+23x+2color(white)(aaaaa)aaaaa-color(white)(aaaaa)aaaaa++color(white)(aaa)aaa||color(white)(aaaa)aaaa++

color(white)(aaaa)aaaax-4x4color(white)(aaaaaa)aaaaaa-color(white)(aaaaa)aaaaa-color(white)(aaa)aaa||color(white)(aaaa)aaaa++

color(white)(aaaa)aaaaf(x)f(x)color(white)(aaaaaaa)aaaaaaa++color(white)(aaaaa)aaaaa-color(white)(aaa)aaa||color(white)(aaaa)aaaa++

Therefore,

f(x)<0f(x)<0, when x in (-2/3,4)x(23,4)

graph{(3x+2)/(x-4) [-28.86, 28.85, -14.43, 14.45]}