I think it’s B I’m doing a lesson on this kind of stuff right now
The vertex is at (0, 3) so y=a(x-0)²+3, which is y=ax²+3
next, use a given point to find a: 10=a(3)²+3, so 9a=7, a=7/9
the equation is then y=

as for the first question, the shape is an ellipse, the domain is -5≤x≤5, the range is -3≤y≤3
the equation can be written as :
Answers:
x = 8
y = 15*sqrt(2)
===========================================================
Explanation:
This is a 45-45-90 triangle. The right triangle is isosceles.
This means the two legs 3x-9 and x+7 are the same length
3x-9 = x+7
3x-x = 7+9
2x = 16
x = 16/2
x = 8
If x = 8, then each leg is...
3x-9 = 3(8)-9 = 24-9 = 15
x+7 = 8+7 = 15
Each leg is 15 units long to help confirm we have the correct x value.
---------------
The hypotenuse y is exactly sqrt(2) times that of the leg length.
Therefore, y = 15*sqrt(2) since earlier we found each leg is 15 units long.
15*sqrt(2) = 21.213 approximately
16.4041995 rounding that would be 16 rounding to the nearest hundredth would be 16.400 (or 16.4) yards.