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Maths year 11

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Original post by z_o_e
I need an introduction haha I know a bit of this :smile:
:awesome:



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
(edited 7 years ago)
Reply 341
Original post by B_9710
There are very simple rules you need to follow to answer all of these questions.
a×b=ab \sqrt a \times \sqrt b = \sqrt{ab} and also
ab=ab \displaystyle \frac{\sqrt a}{\sqrt b }= \sqrt{\frac{a}{b}} .


Your messages come in different forms latex? I'm using my phone for tsr x

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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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Spoiler

Reply 343
Original post by 34908seikj

Spoiler



Where did you get this 9=3 from?



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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
Reply 345
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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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
(edited 7 years ago)
Reply 347
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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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.
Reply 349
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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Reply 350
Anyone needs help!!Ask me,I am here to help you guys.
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
Reply 352
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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Yup! Try the other question by yourself now, see how far you get.
Reply 354
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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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 :biggrin:
Reply 356
Original post by 34908seikj
That's right. Rationalising is really straight forward, so yes I think you should :biggrin:


I'll do one last question on this without looking back at my notes xx

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Reply 357
Original post by 34908seikj
That's right. Rationalising is really straight forward, so yes I think you should :biggrin:




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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.
Reply 359
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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