posted by Troy on .
Can someone check my answers.
Write the following equations in standard form.
1) x^2 - 2x + y^2 + 4y = 11
answer: (x-1)^2 + (y+2)^2 = 16
2) 4x^2 + 24x - y + 34 = 0
answer: y = 4(x-3)^2 + 2
3) The graph of which equation is a circle?
A. 5x^2 + 10x = 9 + 5y^2
B. 5x^2 - 10x = 0 - 5y^2
C. 5x^2 + 5x + y^2 = 9
4)Find the exact solution (s) of each system of equations:
x^2 + y^2 = 25 and 9y = 4x^2
answer: (3,4) (-3,4)
5)Which is the equation of an ellipse with center (-4,2) and a horizontal major axis?
answer: (x+4)^2/16 + (y-2)^2/4 = 1
2 is wrong. Recheck your math regarding the constant.
In 3, C is not a circle because the coefficients of x^2 and y^2 are not equal and not on the same side of the = sign. For a circle, one must to be able to rewrite it as
(x-a)^2 + (y-b)^2 = constant
Would #2 be y=4(x+3)^2-2 and #3 5x^2-10x=0-5y^2?