4. Nolan would like to buy a computer that costs $1,476. Working as a
1 answer:
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Answer:
- Part (a) Vertex = (-3, -1)
- Part (b) Vertex = (4, 5)
- Part (c) function 2; max value = 5
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Explanations:
Part (a)
In this case, the vertex is the highest point, so the vertex of function 1 is (-3, -1)
If the parabola was flipped so that it opened upward, instead of downward, then the vertex would be the lowest point.
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Part (b)
We could graph this function to see where the highest or lowest point is, but there's another way we could find the vertex using algebra.
The given equation is in the form y = ax^2 + bx + c where in this case
- a = -2
- b = 16
- c = -27
The a and b values are plugged into the formula below to get
h = -b/(2a)
h = -16/(2*(-2))
h = -16/(-4)
h = 4
This is the x coordinate the vertex since the vertex is (h,k)
To find k, we plug that value of h into the original function to find its corresponding y value.
y = -2x^2 + 16x - 27
y = -2(4)^2 + 16(4) - 27
y = -2(16) + 16(4) - 27
y = -32 + 64 - 27
y = 5
We found that h = 4 leads to k = 5. The vertex is (h,k) = (4, 5)
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Part (c)
We'll compare the y values of each vertex
- Function 1 has a vertex of (-3, 1)
- Function 2 has a vertex of (4, 5)
The vertex with the larger y value is the winner, so that would be function 2. This parabola reaches a higher peak compared to the other curve.
The max value here is y = 5. In other words, it's the maximum output the function can produce.
If you graphed functions 1 and 2 together on the same xy grid (see below), you'll see that the curve for function 2 reaches a higher peak.
Add 165 to 245. That is a total of 410kWh.
245kWh is more than 50% of 410kWh.
So, according to the plan, you will pay NightTimer rate for kWh at night and DayTimer rate during the day.
The work done:
The raw, accurate, answer is that the value to pay is $22.08085.
In real terms, it is closer to your $22.08 option. That is the one I'd take.