City water, which is slightly chlorinated, is being used to flush a tank of heavily chlorinated water. The concentration C, in milligrams per gallon, of chlorine in the tank 
hours after flushing begins is given by
?
.
The water in the tank is safe for use when chlorine levels are less than 2.50 milligrams per gallon. For what values of t is the water in the tank safe for use? Round your answer to two decimal places.
?
A. 
hours
B. 
hours
C. 
hours
D. 
hours
Answer: D
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Graph the exponential function.y = 5x 
A. 
B. 
C. 
D. 
y?? ? 7y? ?8y = 0 1
What will be an ideal response?
Eliminate the parameter t. Find a rectangular equation for the plane curve defined by the parametric equations.x = 7 sin t, y = 7 cos t; 0 ? t ? 2?
A. y = 
= 49; -? < x < ?
B. y2 - x2 = 49; -? < x < ?
C. y = x2 - 9; -2 ? x ? 2
D. x2 + y2 = 49; -7 ? x ? 7
Solve. Round to the nearest tenth.One end guy wire is attached to the top of a 28-foot pole and the other end is anchored into the ground 21 feet from the base of the pole. Find the length of the guy wire.
21 feet
A. 34.3 ft B. 49 ft C. 35 ft D. 49.7 ft