Himpunan progression dari : x-y-1 = 0 dan x kuadrat + y kuadrat + 5x -9 = 0

X – y – 1 = 0 –> y = x – 1 sub  ke x^2 +y^2 + 5x -9 = 0
x^2 +(x-1)^2 +5x – 9 = 0
x^2 +x^2 – 2x +1 + 5x – 9 = 0
2x^2 + 3x -8 = 0
x^2 + 3/2 x – 4 = 0
(x^2 + 3/2x ) = 4
(x + 3/4)^2 = 4 + 9/16 = 73/16
x + 3/4 = 1/4 √73  atau x+ 3/4 = – 1/4 √73
x1 = 1/4√73 – 3/4  atau x  =  - 1/4 √73  - 3/4
..
y1 = x1 – 1 –> y1 = 1/4√73  - 7/4 
y2 = x2 – 1 –> y2 = - 1/4√73 -7/4