Solve the problem.A ball is thrown upward with an initial velocity of 21 meters per second from a cliff that is 
high. The height of the ball is given by the quadratic equation 
where h is in meters and t is the time in seconds since the ball was thrown. Find the time that the ball will be 20 meters from the ground. Round your answer to the nearest tenth of a second.
A. 7.3 seconds
B. 7.4 seconds
C. 7.8 seconds
D. 7.7 seconds
Answer: A
Mathematics
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Write a numerical expression for the phrase and simplify it.17 less than the difference between 8 and -3
A. 17 - [8 - (-3)]; 6 B. (8 - 3) - 17; -12 C. [8 - (-3)] - 17; -6 D. [8 - (-3)] - 17; -12
Mathematics
Simplify.3
(
- 
)
A. 9x - 3x2
B. 3x
- 3x2
C. 3x
- 3x2
D. 9x - 3x6
Mathematics
Choose the most reasonable unit of measure.Paperback book height: 20 
(mm, cm, m, km)
A. mm B. km C. m D. cm
Mathematics
Factor out the GCF from the polynomial.8x - 56
A. 8x - 7 B. 8(x - 56) C. 8(x - 7) D. -448x
Mathematics