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emmasim [6.3K]
3 years ago
13

Rosa throws a ball. The equation d = −t^2 + 4t + 5 represents the path taken by Rosa's ball where d is the height of the ball (i

n feet) after t seconds. How long was the ball in the air?
A. 1 second
B. 4 seconds
C. 5 seconds
D. 9 seconds
Mathematics
2 answers:
satela [25.4K]3 years ago
5 0

Answer:

B

Step-by-step explanation:

-t²+4t+5=0

t²-4t-5=0

t²-5t+t-5=0

t(t-5)+1(t-5)=0

(t-5)(t+1)=0

t=5,-1

when t=0,d=5

actual time it it is in air=5-1=4 seconds.

Rainbow [258]3 years ago
5 0
If I did the math correctly, it should be B
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Step-by-step explanation:

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thus the interception points are 5/6 and -5/6. By evaluating in 0, we can conclude that the curve y=25 is above the other curve and b should be between 0 and 25 (note that 0 is the smallest value of 36 x²).

The area of the bounded region is given by the integral

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The whole region has an area of 250/9. We need b such as the area of the region below the curve y =b and above y=36x^2 is 125/9. The region would be bounded by the points z and -z, for certain z (this is for the symmetry). Also for the symmetry, this region can be splitted into 2 regions with equal area: between -z and 0, and between 0 and z. The area between 0 and z should be 125/18. Note that 36 z² = b, then z = √b/6.

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