You are Here: Home >< Maths

Announcements
1. hi guys

please can someone help me with understanding the question? the use of the quadratic formula is fine, and maybe i'm being a bit slow here, but i don't understand the second line in the answer - "the difference in roots is ... " where do we get the 1/2 from, and although I know the difference is supposed to be 2, why exactly do we make the equation equal to 2?

2. The quadratic formula gives you two roots. The difference between the two roots is one root subtracted from the other one. If you actually do that subtraction, should get to the second line in the answer.

The question tells you that the difference between the roots is 2, so you are entitled to make your expression obtained above equal to 2.

From there, it's just a matter of rearranging the equation to make c the subject.
3. the point on the x axis exactly half way between the roots is -b/2a.... the distance from this point to the right hand root is {√( b2 - 4ac)}/2a

so you need to double that distance to find the separation of the two roots.

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: October 19, 2017
Today on TSR

### Uni league tables

Do they actually matter?

### University open days

• University of Warwick
Sat, 20 Oct '18
• University of Sheffield
Sat, 20 Oct '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 20 Oct '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