# simultaneous equations

• Oct 19th 2009, 02:28 AM
mark
simultaneous equations
hi i've got the question: solve the simultaneous equations \$\displaystyle 2x + y = 9\$ and \$\displaystyle (x - 2)^2 + y^2 = 5\$

can someone show me how this would be done please? thanks
• Oct 19th 2009, 02:40 AM
Quote:

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

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

HI

\$\displaystyle 2x+y=9\$ --1

From 1 , \$\displaystyle y=9-2x\$

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

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

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

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

\$\displaystyle x=4\$

\$\displaystyle y=9-2(4)\$

\$\displaystyle
=1
\$
• Oct 19th 2009, 04:50 AM
stapel
Quote:

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! (Wondering)

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