Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    2
    ReputationRep:
    Hi so I am resitting C4 because I was one mark off an A overall and I haven't done maths since last June so it's all a bit foreign right now.

    I am doing adding and subtracting polynomials right now and I have come across a problem with showing a polynomial is bigger than a number.

    The question is-

    Given that x>0, show that (x/(x+2)) + ((x+1)(x+6)/(x^2+2x)) >2

    So I have got to the stage where I have (2x+3)/x (I've done all the actual subtracting polynomials work) but how do I show that it's bigger than 2?? I tried putting (2x+3)/x = 0 and = 2 but it's not helping my mind blockage.

    Can anyone put me out of my misery please? I am assuming it is such a dead easy thing to do, I just can't remember how to do it. Thanks guys
    Offline

    3
    ReputationRep:
    If x>0 then (2x+3)/x = 2 + 3/x > 2 since 3/x > 0
    Offline

    14
    ReputationRep:
    \dfrac{2x+3}{x} = 2 + \dfrac{3}{x}

    Now given that x > 0, what can you guarantee about the value of \dfrac{3}{x}?
    • Thread Starter
    Offline

    2
    ReputationRep:
    Ahhh you split it up and then because 3/x is always bigger than 0, then that makes the answer always bigger than 2. I can't believe how obvious that is and I couldn't even see it lol. Thank you
 
 
 
Poll
Who is your favourite TV detective?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.