which of the following equations represents a parabola that opens up and has a vertex with a positive x-value?

a) y=-x^2+8x-15
b) y=2x^2-16x+38
c) y=2x^2+16x+24
d) y=-4x^2-14x-12

maximum area = xy = (16)(32) = 512 ft2

to maximize the area of the garden, the side of the fence parallel to the side of the house should be 32 ft long, and the other two sides should both have length 16 ft.'

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