ANSWER

EXPLANATION
The quadratic equation is:

Group variable terms:

Add the square of half, the coefficient of y to both sides.


The LHS us now a perfect square trinomial:

Take square root:


The first choice is correct.
Do you by any chance have a diagram of the circle or the r value?
Answer:
Step-by-step explanation:
9. disagree;
error: he should have divided 60 by 4, not subtracted. So the correct answer is x = 15.
10. disagree;
error: it should be 3x + 2 = 127 (opposite angles)
so x = 125/3
So: A + C = 180°
X + 20° + 110° = 180°
Then:
X = 50°