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# C1 help! watch

1. Please help it would be much appreciated as i need to fathom this before i move on! Thanks guys and girls
Solve simultaneous equations:

3a+b=8
3a^2+b^2=28
Rearrange eq 1: b=3a

Sub it into 2: 3a^2+(8-3a)^2=28
You get -6a^2-48a+64=28
-6a^2-48a+36=0

I then divided it by -6 to get: a^2+8a-6=0
Im stuck here where theres no numbers that x to get -6 and + to get 8. What should i do or have i made a mistake? Please explain! Thanks
2. I didn't get: -6a^2-48a+36=0.

Try doing this step by step:

3a+b=8
therefore, b=8-3a
3a^2+b^2-28=0
Sub in.

Then you get 3a^2+(8-3a)^2-28=0
Expand.
3. (Original post by YsfAli)
Please help it would be much appreciated as i need to fathom this before i move on! Thanks guys and girls
Solve simultaneous equations:

3a+b=8
3a^2+b^2=28
Rearrange eq 1: b=3a

Sub it into 2: 3a^2+(8-3a)^2=28
You get -6a^2-48a+64=28
-6a^2-48a+36=0

I then divided it by -6 to get: a^2+8a-6=0
Im stuck here where theres no numbers that x to get -6 and + to get 8. What should i do or have i made a mistake? Please explain! Thanks
Hi,
Hint: you made the mistake when you squared -3a. Re-check that bit.
Hope this helps!
4. (Original post by Reety)
I didn't get: -6a^2-48a+36=0.

Try doing this step by step:

3a+b=8
therefore, b=8-3a
3a^2+b^2-28=0
Sub in.

Then you get 3a^2+(8-3a)^2-28=0
Expand.
Thanks bro, did just realise my silly mistake. Thanks anyway!
5. (Original post by Angel28)
Hi,
Hint: you made the mistake when you squared -3a. Re-check that bit.
Hope this helps!
Yeah i did a silly mistake should have spotted that. Thanks for the help!
6. (Original post by YsfAli)
Thanks bro, did just realise my silly mistake. Thanks anyway!
Spoiler:
Show
7. (Original post by YsfAli)
Yeah i did a silly mistake should have spotted that. Thanks for the help!
No problem

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