You are Here: Home >< Maths

# C1 inequalities help please watch

1. Hi just doing the 2005 jan OCR c1 paper and stuck on question 8iii

The length of a rectangular children's playground is 10m more than it's width. The width of the playground is Xm

i) The perimeter of the playground is greater than 64m. Write down a linear inequality in X

ii) The area of the playground is less than 299m^2. Show that (X-13)(X+23)<0

iii) By solving the inequalities in parts i and ii, determine the set of possible values of x

Ok so managed i and ii fine, by i being 4X + 20 > 64 and ii being proven

Stuck on part iii though..

Have determined x>11 by re-arranging part i but not sure how to go about the rest of it..

Thanks!
2. Can you solve the quadratic inequality (X-13)(X+23)<0 ? Consider a sketch.
Then combine the solution with the other one x>11.
3. Do you know how to sketch ?

For what x values would y be less than 0 ?

Don't forget that x also has to be greater than 11. Combine these pieces of information.
4. (Original post by vc94)
Can you solve the quadratic inequality (X-13)(X+23)&lt;0 ? Consider a sketch.
Then combine the solution with the other one x&gt;11.
ahhhh!!!

So from sketching gives the inequalities -23<x<13

and x>11 from using part i

So 11<x<13 !

Thank you!

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 28, 2011
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

Wed, 25 Jul '18
2. University of Buckingham
Wed, 25 Jul '18
3. Bournemouth University
Wed, 1 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams