Question

Complete the square to put he equation in convenient form for graphing. Then graph the conic section

Answer 1

First off, I think the equation should have a negative 9 in it originally and then you move it to the other side and it becomes positive.

You'll basically complete the square for two equations at the same time. Set it up like this:

(16x^2 + 96x) + (9y^2 - 18y) = 9

Divide everything by 16 to get the x^2 by itself, then divide everything by 9 to get y^2 by itself. You should end up with this.

(x^2 + 6x) + (y^2 - 2y) = 9/144

then complete the square by taking the second term of each polynomial, dividing by two, and squaring it.

For instance the first one will be 6/2 = 3^2 = 9

The next one will be 2/2 =1^2 = 1

Add these to numbers to the polynomials as well as to the other side of the equation to keep it equal. You should end up with this.


(x^2 + 6x+9) + (y^2 - 2y+1) = (9/144)+9+1

Then find a common denominator on the right side of the equals sign and add them all together to get:

(x^2 + 6x+9) + (y^2 - 2y+1) = 1449/144

Factor out the two polynomials

(x+3)^2 + (y-1)^2 = 1449/144

the center of the circle is (-3,1) according to the factored out polynomials and the radius will be the square root of the number on the right side of the equals sign = sqrt(1449/144) = 3.17