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# C1 simultaneous equation help! watch

1. 2x+y=1
x^2+y^2=1

rearranged eq 1 which is y=1-2x
sub into eq 2 which is x^2+(1-2x)^2=1
which is 5x^2-4x+1=1
then you have to make it quad by moving 1 left
5x^2-4x+1-1 which cancels the 1's out which leaves it 5x^2-4x? dont get it
2. you've done all the hard work!

You can factor out the x giving x(5x-4) = 0 then x = 0 or 4/5

When x = 0 y = 1 when x = 4/5 y = -3/5
3. (Original post by YsfAli)
2x+y=1
x^2+y^2=1

rearranged eq 1 which is y=1-2x
sub into eq 2 which is x^2+(1-2x)^2=1
which is 5x^2-4x+1=1
then you have to make it quad by moving 1 left
5x^2-4x+1-1 which cancels the 1's out which leaves it 5x^2-4x? dont get it
You have forgotten the '= 0'; taking away 1s from both sides leaves you with 5x^2 - 4x = 0, which is easy to factorise. As skeptical_john said, you've done the hard work already.
4. (Original post by skeptical_john)
you've done all the hard work!

You can factor out the x giving x(5x-4) = 0 then x = 0 or 4/5

When x = 0 y = 1 when x = 4/5 y = -3/5
yes i didnt think of that. was just thinking of putting it in the form of ax^2+b+c. Thanks!
btw is 2(3x)^2 18x or 12x? Thanks!

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Updated: September 7, 2015
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