At a concession stand, 9 slices of pizza and 5 soft pretzels cost $33.25. If 6 soft pretzels and 4 slices of pizzas cost $19.50,
what is the cost of a soft pretzel and a slice of pizza?
2 answers:
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Answer:
-3 1/3
Step-by-step explanation:
The quadratic
... y = ax² +bx +c
has its extreme value at
... x = -b/(2a)
Since a = 3 is positive, we know the parabola opens upward and the extreme value is a minimum. (We also know that from the problem statement asking us to find the minimum value.) The value of x at the minimum is -(-4)/(2·3) = 2/3.
To find the minimum value, we need to evaluate the function for x=2/3.
The most straightforward way to do this is to substitue 2/3 for x.
... y = 3(2/3)² -4(2/3) -2 = 3(4/9) -8/3 -2
... y = (4 -8 -6)/3 = -10/3
... y = -3 1/3
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<em>Confirmation</em>
You can also use a graphing calculator to show you the minimum.
