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.

DM
Answered by David M. Further Mathematics tutor

5561 Views

See similar Further Mathematics A Level tutors

Related Further Mathematics A Level answers

All answers ▸

Prove that sum(k) from 0 to n is n(n+1)/2, by induction


The ODE mx'' + cx' + kx = 0 is used to model a damped mass-spring system, where m is the mass, c is the damping constant and k is the spring constant. Describe and explain the behaviour of the system for the cases: (a) c^2>4mk; (b) c^2=4mk; (c) c^2<4mk.


Prove by induction that the sum of the first n integers can be written as (1/2)(n)(n+1).


a) Find the general solution to the differential equation: f(x)=y''-12y'-13y=8. b) Given that when x=0, y=0 and y'=1, find the particular solution to f(x).


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning