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# Simultaneous Equation Help... watch

1. How would you solve:

y=4x+4
x^2+y^2=36

Basically, if the x^2+y^2=36 was on the top it would be easy, but it is at the bottom, so now I'm stuck...

2. It don't matter where they are

Substitute y = 4x + 4 into the second one

And couldn't you just post this in the other thread
3. how?
4. you do x^2 + (4x+4)^2 = 36, then work out the value for x to find the value for y
btw what work is this?? gcse, as level...?
5. (Original post by Sophie Maywood)
How would you solve:

y=4x+4
x^2+y^2=36

Basically, if the x^2+y^2=36 was on the top it would be easy, but it is at the bottom, so now I'm stuck...

<--- 1
<--- 2

substitute 1 into 2

we know what y is equal to don't we?
and i can see a y in the 2nd equation..

therefore we can square our first equation to get

and so we can put this into the 2nd equation by replacing the

so we get:

expand that out and you get ..... i'll not go on unless you're still wondering what to do next, because you should see the quadratic now
6. (Original post by Sophie Maywood)
How would you solve:

y=4x+4
x^2+y^2=36

Basically, if the x^2+y^2=36 was on the top it would be easy, but it is at the bottom, so now I'm stuck...

What do you mean it would be easier if x^2+y^2=36 was on the top? how would they be any diferent if the other way round, or maybe even side by side?

x^2+y^2=36 y=4x+4

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