Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter

    Name:  hard inequality.jpg
Views: 7
Size:  73.4 KB
    Attached Images
    • Very Important Poster

    Very Important Poster
    (Original post by 10DannyRush)
    Name:  hard inequality.jpg
Views: 7
Size:  73.4 KB
    What have you tried so far?
    • Community Assistant

    Community Assistant
    (Original post by 10DannyRush)
    2. Multiply through by x^2(x+3)^2, get everything on one side, and fully factorise. Draw a rough sketch of what the factorised quartic looks like then deduce the answer from the sketch.

    3b. You can use the method of differences to deduce \displaystyle \sum_{r=1}^n r^3-(r-1)^3. Then make this equal to \displaystyle 3 \sum_{r=1}^n r^2 - 3 \sum_{r=1}^n r - \sum_{r=1}^n 1.

    You know the latter two sums in terms of n, so just rearrange for \displaystyle \sum_{r=1}^n r^2
How are you feeling about your exams?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


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