# Simultaneous Equations

• November 22nd 2009, 07:07 AM
Mukilab
Simultaneous Equations
Just a simultaneous equation I've found and need help on.

x^2 + y^2 = 5
y = 3x + 1

• November 22nd 2009, 07:21 AM
skeeter
Quote:

Originally Posted by Mukilab
Just a simultaneous equation I've found and need help on.

x^2 + y^2 = 5
y = 3x + 1

substitute for y and solve ...

$x^2 + (3x+1)^2 = 5$

you'll get two solutions where the line intersects the circle.
• November 22nd 2009, 07:36 AM
Mukilab
did that and got a 9x^2 before....

Confused how to get the final product. That's kind of what I was asking for?
• November 22nd 2009, 07:45 AM
skeeter
Quote:

Originally Posted by Mukilab
did that and got a 9x^2 before....

Confused how to get the final product. That's kind of what I was asking for?

$x^2 + (3x+1)^2 = 5$

$x^2 + 9x^2 + 6x + 1 = 5$

$10x^2 + 6x - 4 = 0$

$5x^2 + 3x - 2 = 0$

factor and solve.
• November 22nd 2009, 07:48 AM
Mukilab
thank you