You are Here: Home >< Maths

# C4 help watch

1. (Original post by pondsteps)
Yeah you just substitute in the zero and put the sign right
Lol pretty much for t = 0.
y = 2t..., when t = 0, y = 2 * 0 = 0.
y = 2t, if t > 0, y > 0 because t is positive and 2 is positive, +ve * +ve = +ve which is > 0.
That's simple, you can just sub in any values of t > 0 into y and see the trend: y > 0.

Read the explanation above and if you don't understand it, try it for t < 0, where x = t^2 - 2. You will see all your values tend to -2 or go further away from it. The smaller t is the further away it is from -2 (it is larger than it) and the greater it is when it is negative so e.g. -4, -3, -2, -1 ... (or closer to 0) the closer it is to -2, but it will never reach -2 except t = 0. So, you will be able to conclude: when t < 0, x > -2.

### 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: February 11, 2017
Today on TSR

### Edexcel GCSE Maths Unofficial Markscheme

Find out how you've done here

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