Unformatted text preview: 10 y  1 = 0 [Solution]
Solution
Neither of these equations are in standard form and so to determine the center and radius well
need to put it into standard form. We actually already know how to do this. Back when we were
solving quadratic equations we saw a way to turn a quadratic polynomial into a perfect square.
The process was called completing the square.
This is exactly what we want to do here, although in this case we aren’t solving anything and
we’re going to have to deal with the fact that we’ve got both x and y in the equation. Let’s step
through the process with the first part.
(a) x 2 + y 2 + 8 x + 7 = 0
We’ll go through the process in a step by step fashion with this one.
Step 1 : First get the constant on one side by itself and at the same time group the x terms
together and the y terms together. x 2 + 8 x + y 2 = 7
In this case there was only one term with a y in it and two with x’s in them.
Step 2 : For each variable with two terms complete the square on those terms.
© 2007 Paul Dawkins 172 http://tutorial.math.lamar.edu/...
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This note was uploaded on 06/06/2012 for the course ICT 4 taught by Professor Mrvinh during the Spring '12 term at Hanoi University of Technology.
 Spring '12
 MrVinh

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