x Turn on thread page Beta
 You are Here: Home >< GCSEs

# Maths watch

1. Hi. How would you write (2+square root of 5)^(2) in the form
a+b x (square root of 5).

So far I have got that 2^(2) = 4 and root 5 squared = root 25 which is 5. Is that right?
I don't know where to go from here.
2. 2+2 is 4, minus 1 that's 3. Quick maths.
3. (Original post by RenéDescartes)
2+2 is 4, minus 1 that's 3. Quick maths.
Very funny.
4. (Original post by Maths1210)
Very funny.
Everyday mans on the block. Smoke trees.
5. Remember (A + B)^2 = A^2 + 2AB + B^2

It does not equal A^ + B^2
6. You can't square them individually, its a bracket multiplying a bracket so (2+sqrt5)(2+sqrt5)=??
7. working with roots can be difficult and confusing, for some. For me, the best way to do this question is to treat is as algebra; imagine (or replace if you need visual help) the /5 with x (or any other algebra term). Firstly you have to get rid of the (^2) so:

( key: / = square root) :

(2+/5)^2 -> (2+/5) x (2+/5) (expand the question so you can visually see what you have to do)

(2+/5) x (2+/5) (once you are comfortable with these types of questions, you can skip some steps like visually expanding although examiners sometimes want to see how you do it)

= (2x2)+(2x/5)+(/5x2)+(/5x/5) (this is multiplying out the brackets)

= 4+ 2/5 + 2/5+ 5 (working out inside the brackets)

= 9 +2/5 +2/5 (simplify by adding likely terms)

=9+ 4/5 (imagine they asked to add 2x+2x, you would get 4x)

so a=9 and b=4.

If there's anything you didn't understand, write back. Hope this helps!
8. (Original post by number0)
Remember (A + B)^2 = A^2 + 2AB + B^2

It does not equal A^ + B^2
I don't know what you mean by 2AB. Could you explain that please?
9. (Original post by Maths1210)
I don't know what you mean by 2AB. Could you explain that please?
it means 2 x A x B. The x means multiply.
10. (Original post by evelina s)
working with roots can be difficult and confusing, for some. For me, the best way to do this question is to treat is as algebra; imagine (or replace if you need visual help) the /5 with x (or any other algebra term). Firstly you have to get rid of the (^2) so:

( key: / = square root) :

(2+/5)^2 -> (2+/5) x (2+/5) (expand the question so you can visually see what you have to do)

(2+/5) x (2+/5) (once you are comfortable with these types of questions, you can skip some steps like visually expanding although examiners sometimes want to see how you do it)

= (2x2)+(2x/5)+(/5x2)+(/5x/5) (this is multiplying out the brackets)

= 4+ 2/5 + 2/5+ 5 (working out inside the brackets)

= 9 +2/5 +2/5 (simplify by adding likely terms)

=9+ 4/5 (imagine they asked to add 2x+2x, you would get 4x)

so a=9 and b=4.

If there's anything you didn't understand, write back. Hope this helps!
Thank you this really helped. I always forget to put it into brackets.

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 4, 2018
Today on TSR

### Boyfriend slept with someone else

...we were on a break

Poll
Useful resources

## Study tools

### Essay expert

Learn to write like a pro with our ultimate essay guide.

See where you can apply with our uni match tool

### Make study resources

Create all the resources you need to get the grades.

### Create your own Study Plan

Organise all your homework and exams so you never miss another deadline.

### Resources by subject

From flashcards to mind maps; there's everything you need for all of your GCSE subjects.

### Find past papers

100s of GCSE past papers for all your subjects at your fingertips.