# Thread: simultaneous equations

1. ## simultaneous equations

hi i've got the question: solve the simultaneous equations $2x + y = 9$ and $(x - 2)^2 + y^2 = 5$

can someone show me how this would be done please? thanks

2. Originally Posted by mark
hi i've got the question: solve the simultaneous equations $2x + y = 9$ and $(x - 2)^2 + y^2 = 5$

can someone show me how this would be done please? thanks
HI

$2x+y=9$ --1

From 1 , $y=9-2x$

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

Substitute $(x-2)^2+(9-2x)^2=5$

$x^2-4x+4+81-36x+4x^2-5=0$

$x^2-8x+16=0$

$x=4$

$y=9-2(4)$

$
=1
$

3. Originally Posted by mark
can someone show me how this would be done please?
Ouch! They were supposed to have covered this in class and in your text before assigning questions on it!

To learn "how this would be done", try an online lesson or two. Be sure to study the worked examples.