Question

how to convert to standard form by completing the square on x and y.

9x^2+4y^2-72x+16y+124=0

Answer 1

9(x^2 - 8x + ....) + 4(y^2 + 4y + ....) = -124

9(x^2 - 8x + 16) + 4(y^2 + 4y + 4) = -124 + 144 + 16
9(x-4)^2 + 4(y+2)^2 = 36

divide each term by 36
(x-4)^2 /4 + (y+2)^2 /9 = 1