X^2 + 6x - 7 =
(x + 7)(x - 1)
Note the general equation of a circle is x^2 + y^2 = r^2, with centre (0, 0) and radius: r.
So, our equation of a circle is (x + 3)^2 + (y - 1)^2 = 100
Subtract 100 from both sides and plug in the points. If it equals to 0, then the points satisfy the equation of the circle (ie lies on the circle)
Answer:
x = -7
Step-by-step explanation:
To find the value of x, you need to set up a proportion:
= 
Then cross multiply:
15x - 15 = 18x + 36
Then subtract 15x from both sides:
-15 = 3x + 36
Subtract 36 from both sides:
-51 = 3x
Finally, divide both sides by 3:
x = -7