The Student Room Group

Maths

What is 51-14 sqrt 2 divided by 3 -2 sqrt 2

Scroll to see replies

Original post by Elisa2000
What is 51-14 sqrt 2 divided by 3 -2 sqrt 2


It's a secret

Spoiler

Reply 2
Original post by EricPiphany
It's a secret

Spoiler



What did you get overall?
Original post by Elisa2000
What did you get overall?


I didn't. What did you get?
Reply 4
Original post by EricPiphany
I didn't. What did you get?


I got 41 -20 sqrt 2
Original post by Elisa2000
I got 41 -20 sqrt 2


Try again.
Reply 6
Original post by RDKGames
Try again.


Well, could you show me what the right answer is? Without using a calculator
Original post by Elisa2000
Well, could you show me what the right answer is? Without using a calculator


Show your working and I'll tell you where you went wrong.
Reply 8
Original post by RDKGames
Show your working and I'll tell you where you went wrong.


51 - 14 sqrt 2/ 3 -2 sqrt 2 both multiplied by 3+2 sqrt 2. Then I got 153 + 102 sqrt 2 - 42 sqrt 2 - 28 - 2 divided by 9-4-2 which gave me: 123-60 sqrt 2 /3. I divided it by three, which gave me 41 -20 sqrt 20
Original post by Elisa2000
What is 51-14 sqrt 2 divided by 3 -2 sqrt 2

51142322\frac{51-14\sqrt{2}}{3-2\sqrt{2}}?
Reply 10
Original post by XOR_
51142322\frac{51-14\sqrt{2}}{3-2\sqrt{2}}?


Could you help me with this?
Original post by Elisa2000
51 - 14 sqrt 2/ 3 -2 sqrt 2 both multiplied by 3+2 sqrt 2. Then I got 153 + 102 sqrt 2 - 42 sqrt 2 - 28 - 2 divided by 9-4-2 which gave me: 123-60 sqrt 2 /3. I divided it by three, which gave me 41 -20 sqrt 20


Well you simply multiplied wrong.

Numerator: (51142)(3+22)=51(3+22)142(3+22)(51-14\sqrt{2})(3+2\sqrt{2})=51(3+2 \sqrt{2})-14\sqrt{2}(3+2\sqrt{2})

=153+10224222822=153+102 \sqrt{2}-42\sqrt{2}-28\sqrt{2} \sqrt{2}

Denominator: (322)(3+22)=9422(3-2\sqrt{2})(3+2\sqrt{2})=9-4\sqrt{2}\sqrt{2}

Now simplify and carry on.
(edited 7 years ago)
Reply 12
multiply top and botton by (3 + 2(sqrt2)) to rationalize the denominator

EDIT: left for a few minutes and was answered i cri erry tim
(edited 7 years ago)
Original post by RDKGames
Well you simply multiplied wrong.

Numerator: (51142)(3+22)=51(3+22)142(3+22)(51-14\sqrt{2})(3+2\sqrt{2})=51(3+2 \sqrt{2})-14\sqrt{2}(3+2\sqrt{2})

=153+10224222822=153+102 \sqrt{2}-42\sqrt{2}-28\sqrt{2} \sqrt{2}

Denominator: (322)(3+22)=9422(3-2\sqrt{2})(3+2\sqrt{2})=9-4\sqrt{2}\sqrt{2}

Now simplify and carry on.

isn't it 3-2sqrt(2)
Original post by XOR_
isn't it 3-2sqrt(2)


Huh? Where?
Original post by RDKGames
Huh? Where?

The original questions' denominator.
(edited 7 years ago)
Reply 16
If you want my answer:

Spoiler

(edited 7 years ago)
Original post by XOR_
The original questions' denominator.


Yes it is. I'm showing multiplication by the conjugate of it.
Original post by Notch
If you want my answer:

Spoiler



Close.
Reply 19
Original post by RDKGames
Well you simply multiplied wrong.

Numerator: (51142)(3+22)=51(3+22)142(3+22)(51-14\sqrt{2})(3+2\sqrt{2})=51(3+2 \sqrt{2})-14\sqrt{2}(3+2\sqrt{2})

=153+10224222822=153+102 \sqrt{2}-42\sqrt{2}-28\sqrt{2} \sqrt{2}

Denominator: (322)(3+22)=9422(3-2\sqrt{2})(3+2\sqrt{2})=9-4\sqrt{2}\sqrt{2}

Now simplify and carry on.


Look, minus sqrt 2 and sqrt 2 when multiplied make minus 2

Quick Reply

Latest