Question

Write the general equation for the circle that passes through the points (1, 1), (1, 3), and (9, 2).

You must include the appropriate sign (+ or -) in your answer. Do not use spaces in your answer.
8x² + 8y² ___x ___y ___ = 0

Answer 1

Explanation:

Answer 2

`8x^2+8y^2-75x-32y+91=0`

Explanation:

For point (1,1)

8*1^2+8*1^2+a*1+b*1+c=0

8+8+a+b+c=0

a+b+c=-16

For point (1,3):

8*1^2+8*3^2+a*1+b*3+c=0

8+72+a+3b+c=0

a+3b+c=-80

For point (9,2):

8*9^2+8*2^2+a*9+b*2+c=0

648+32+9a+2b+c=0

9a+2b+c=-680

From system:

a+b+c=-16.....(1)

a+3b+c=-80....(2)

9a+2b+c=-680....(3)

From (2)-(1) we have:

2b=-64

b=-32.

Now we have

a+c=16

9a+c=-616

i.e,

8a=-600,

a=-75,

and at the end

c=16+75=91