# I'm really stuck on this simultaneous equation

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#1
The question is
Solve the simultaneous equations
y = 3x – 1
x² + y² = 5

0
6 years ago
#2
You need to substitute the first equation into the second so you'd get x2 +(3x-1)2 =5
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#3
(Original post by CH :))
You need to substitute the first equation into the second so you'd get x2 +(3x-1)2 =5
so where does the y go?
0
6 years ago
#4
(Original post by Rockyboy)
...
I'm presuming that's supposed to be:

If so, looking at the first equation, you have in terms of . Therefore, how can you change equation 2 to get an equation just in ?

Hint
Try substituting equation 1 into the of equation two.

If it helps, visualise equation one as . Because that is equal to , you're effectively saying that . I hope that is of help.
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6 years ago
#5
Y = 3x-1. That's what y is. So the y just goes because it IS 3x-1.

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0
6 years ago
#6
You substitute the y into the second to find out your x values, then you use your x values and the first equation to work out y after
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#7
(Original post by CH :))
You substitute the y into the second to find out your x values, then you use your x values and the first equation to work out y after
so the equation will be x² + (3x-1)² =5 when you substitute y into equation 2 ?
1
6 years ago
#8
Yep
0
6 years ago
#9
So expand, simplify and you should have a quadratic that can be factorised
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#10
This makes it much more easier. Thanks to all those who helped me
0
6 years ago
#11
No problem
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