Please help!

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2 If f(ac) = 7+ + find f' (a). Find f' (2).If f(ac) = 7 3(23 - 6\\x + 6), find f' (a). Find f' (5).\fA ball is thrown upward in the air, and its height above the ground after 15 seconds is H(t) = 8913 162:2 feet. Find the time 15 when the ball will be traveling downward at 44.5 feet per second. Give your answer as a decimal approximation with at least 3 decimal places