# Linear systems

• October 10th 2012, 05:11 PM
cheers
Linear systems
so this is the question....

x^2 +y^2=4
y=2x-5

how do i do this???? (show full steps please)
• October 10th 2012, 05:41 PM
TheEmptySet
Re: Linear systems
Quote:

Originally Posted by cheers
so this is the question....

x^2 +y^2=4
y=2x-5

how do i do this???? (show full steps please)

First this is not a linear system. It can be solved by substition

$x^2+(2x-5)^2=4$

This is a quadratic equation. Expand out the parenthesis and sput into standard form and solve.

Post back if you get stuck.
• October 10th 2012, 05:43 PM
skeeter
Re: Linear systems
Quote:

Originally Posted by cheers
so this is the question....

x^2 +y^2=4
y=2x-5

how do i do this???? (show full steps please)

substitute $(2x-5)$ for $y$ in the circle equation ...

$x^2 + (2x-5)^2 = 4$

solve for x , then find y using the linear equation

note you may get more than one solution for x