Determine the interval(s) at which f(x) is concave up given that f′′(x)=−x2+4x+5.

f(x) is concave upward where f''(x) > 0.

f''(x) = -(x -5)(x +1)

This will be greater than 0 for x between the roots of -1 and +5.

f(x) is concave upward on the interval (-1, 5).

answer: you need to organize this better it does not make sense.

step-by-step explanation: ?

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x=0.8898305 is the answer to that equation