Find the set of values for which: 3/(x+3) >(x-4)/x

First we must consider for which values of x the equation: 3/(x+3) = (x-4)/x is undefined. In this case, x=-3, and x=0. 

Now we must consider each of the cases, x<-3, -3<x<0, 0<x

Case 1 (x<-3): if we assume 3/(x+3) > (x-4)/x then it follows, as x<-3, 3x > x2-x-12. Which implies (x-6)(x+2) < 0. For this to hold exactly one of (x-6) and (x+2) must be less than 0 and the other greater than 0. which implies -2<x<4, which is a contradiction therfore not satisfied in the range.

Case 2 (-3<x<0)  x2-4x-12 > 0, which implies (x-6)(x+2) >0. Therefore for x2-4x-12 > 0, either both (x-6) and (x+2) must be less than 0 or greater than 0. therefore x<-2 or x>6. Therefore as we know -3<x<0, it holds for -3<x<-2

Case 3 (x>0): Therefore x2-4x-12 < 0, which implies (x-6)(x+2) < 0. For this to hold exactly one of (x-6) and (x+2) must be less than 0 and the other greater than 0. which implies -2<x<4, thefore the equation holds for 0<x<4

Finally as we have considered all cases the final answer is -3<x<-2 & 0<x<4.

Related Further Mathematics A Level answers

All answers ▸

Given that z = a + bj, find Re(z/z*) and Im(z/z*).


Are we able to represent linear matrix transformations with complex numbers?


Whats the derivative of sin(3x)?


What is the polar form of the equation: x^2+y^2 =xy+1


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences