No. It should be -9x. I just checked through the first
equation with my teacher. She said there's no problem with it. And
this is also the answer given on the answer scheme. So yea, kinda
reliable.
As what Mikethm has said, the centre is (4.5, 0.5)
You solve (x-4.5)^2 +(y-0.5)^2 = 53/2
x^2 - 9x + 81/4 + y^2 - y + 1/4 = 53/2
x^2 + y^2 - 9x - y - 6 =0
Eh... I said that the 2nd equation should have +9x,
not the 1st one.
I said that the 1st circle is (x-4.5)^2+(y-0.5)^2= r^2.
Expanding that would give us -9x which is in agreement with your
(teacher/answer sheet) solution for 1st circle.
The problem is that you said the
2nd circle is x^2 + y^2 + x - y - 6 = 0.
The correct coefficient of x is +9x for 2nd circle.
There is a program called geogebra. Here is what I did to create
the attached image.
1) I request the program to create a circle passing
thru P, Q and R.
2) I request the program to reflect the circle in the
y-axis.
The equations by the side are generated by the program.
