Solve the problem by using an absolute value equation or inequality. See Example 10.Uniden...

Solve the problem by using an absolute value equation or inequality. See Example 10.

Unidentified flying objects. The function

gives the height in feet above the earth at time t seconds for an object projected into the air with an initial velocity of v 0 feet per second (ft/sec) from an initial height of s 0 feet. Two balls are tossed into the air simultaneously, one from the ground at 50 ft/sec and one from a height of 10 feet at 40 ft/sec. See the accompanying graph.

a) Use the graph to estimate the time at which the balls are at the same height.

b) Find the time from part (a) algebraically.

c) For what values of t will their heights above the ground differ by less than 5 feet (while they are both in the air)?

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Figure for Exercise 91