Question 615366: The height, y, of a ball tossed into the air can be represented by the equation y=-x^2+10x+3, where x is the elasped time. How many seconds does it take the ball to reach a height of 28 feet?
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! The height, y, of a ball tossed into the air can be represented by the equation y=-x^2+10x+3, where x is the elasped time. How many seconds does it take the ball to reach a height of 28 feet?
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set y to 28 and solve for x:
y=-x^2+10x+3
28=-x^2+10x+3
0=-x^2+10x-25
0=x^2-10x+25
0=(x-5)(x-5)
x = 5 seconds
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