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# Maths year 11

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1. (Original post by z_o_e)
I need an introduction haha I know a bit of this

Just expand the brackets as you would with normal algebra.

The final answer for the first one is 18+6√5

The rules for surds have already been posted above, try the other questions out.

I'll do the last one which involves rationalising the denominator.

Edit: my answer is slightly wrong I wrote 3√5 instead of 6√5
2. (Original post by B_9710)
There are very simple rules you need to follow to answer all of these questions.
and also
.
Your messages come in different forms latex? I'm using my phone for tsr x

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3. (Original post by z_o_e)
Your messages come in different forms latex? I'm using my phone for tsr x

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4. (Original post by 34908seikj)
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Where did you get this 9=3 from?

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5. (Original post by z_o_e)
Where did you get this 9=3 from?

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√9 = 3

What's 3^2 ? It's 9. So therefore √9 = 3
6. (Original post by 34908seikj)
√9 = 3

What's 3^2 ? It's 9. So therefore √9 = 3
OOOH. SO THIS IS SQUARE ROOT??
Ohh

And I didn't understand what I do after this..

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7. (Original post by z_o_e)
OOOH. SO THIS IS SQUARE ROOT??
Ohh

And I didn't understand what I do after this..

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Multiply. Remember if you multiply the same two numbers together it's equivalent to squaring them. Since you're multiplying a square root number by the same square root number, the square root cancels out and you're just left with the number

e.g. √3*√3 = 3 - or you can think of it like √3*√3 = √9 and √9 = 3

√3 * √15 = √45 since it's just 3*15 under a root. Then you can simply the √45
8. (Original post by 34908seikj)
Multiply. Remember if you multiply the same two numbers together it's equivalent to squaring them. Since you're multiplying a square root number by the same square root number, the square root cancels out and you're just left with the number

e.g. √3*√3 = 3 - or you can think of it like √3*√3 = √9 and √9 = 3

√3 * √15 = √45 since it's just 3*15 under a root. Then you can simply the √45
Do I simplify 90?

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9. (Original post by z_o_e)
Do I simplify 90?

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No, you have two pairs of √45 so it would be 2√45, not √90, you CAN'T add surds like that.
10. (Original post by 34908seikj)
No, you have two pairs of √45 so it would be 2√45, not √90, you CAN'T add surds like that.
Can you do this part please?

On paper and shown it out please x

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12. (Original post by z_o_e)
Can you do this part please?

On paper and shown it out please x

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So you have 3 + √45 + √45 + 15

: 18 + 2√45

√45 Simplifies down to 3√5

So now you have 18 + (2)(3)√5

Which gives you the final answer of 18 + 6√5
13. (Original post by 34908seikj)
So you have 3 + √45 + √45 + 15

: 18 + 2√45

√45 Simplifies down to 3√5

So now you have 18 + (2)(3)√5

Which gives you the final answer of 18 + 6√5
GOT IT !!!

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14. (Original post by z_o_e)
GOT IT !!!

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Yup! Try the other question by yourself now, see how far you get.
15. (Original post by 34908seikj)
Yup! Try the other question by yourself now, see how far you get.
I think I should learn to do these ones then move onto rationalalizing?

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16. (Original post by z_o_e)
I think I should learn to do these ones then move onto rationalalizing?

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That's right. Rationalising is really straight forward, so yes I think you should
17. (Original post by 34908seikj)
That's right. Rationalising is really straight forward, so yes I think you should
I'll do one last question on this without looking back at my notes xx

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18. (Original post by 34908seikj)
That's right. Rationalising is really straight forward, so yes I think you should

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19. I get 54+24√2

You've messed up for working out slightly; you write + for everything when some of the sums should have been multiplied.
20. (Original post by 34908seikj)
I get 54+24√2

You've messed up for working out slightly; you write + for everything when some of the sums should have been multiplied.
I corrected them in red pen.

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