Since the parabola passes by the center its equation is:
y = ax². But it opens downward, that means the coefficient a is negative.
Then the equation becomes:
y = - ax², with x = 0 as its axis of symmetry.
We are given that the height is 84 ft when the opening downward is 42 ft.
That means to the (height) y, corresponds x =+21 & x=-21 (due to symmetry).
In order to calculate a let's plug y & x with their related values:
y = - ax²
84 = - a(21)²
84 = - a(441) and a = - 84/441 ↔ a = - 4/21
And the final equation is : y = -4/21. x²
Answer:
C. (2, 6] hour jobs cost $100
Step-by-step explanation:
Let's consider each of these statements in view of the graph:
- A cleaning time of 2 hours will cost $100. -- The closed circle at (2, 50) tells you the cost of a 2-hour job is $50, not $100.
- A cleaning time of 6 hours will cost $150. -- The closed circle at (6, 100) tells you the cost of a 6-hour job is $100, not $150.
- Cost is a fixed rate of $100 for jobs requiring more than 2 hours, up to a maximum of 6 hours. -- The line between the open circle at (2, 100) and the closed circle at (6, 100) tells you this is TRUE.
- Cost is a fixed rate of $200 for jobs that require at least 6 hours. -- "At least 6 hours" means "greater than or equal to 6 hours." The closed circle at (6, 100) means a 6-hour job is $100, not $200.
Answer:
Please see attachment
Step-by-step explanation:
