Problem

Determine the intervals on which the function is concave up or down and find the points of inflection.
f(x)=8x35x2+6
(Give your answer as a comma-separated list of points in the form (, ). Express numbers in exact form. Use notation and fractions where needed.)

Answer

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Answer

Therefore, the function is concave down on (,5/24) and concave up on (5/24,). The point of inflection is at (5/24,f(5/24))=(5/24,8(5/24)35(5/24)2+6)

Steps

Step 1 :First, we find the first derivative of the function, which is f(x)=24x210x.

Step 2 :Next, we find the second derivative of the function, which is f(x)=48x10.

Step 3 :To find the points of inflection, we set the second derivative equal to zero and solve for x: 48x10=0, which simplifies to x=5/24.

Step 4 :We then test the intervals around the point of inflection in the second derivative. For x<5/24, we use x=0 and find that f(0)=10, which is less than 0. Therefore, the function is concave down on the interval (,5/24).

Step 5 :For x>5/24, we use x=1 and find that f(1)=38, which is greater than 0. Therefore, the function is concave up on the interval (5/24,).

Step 6 :Finally, we find that the point of inflection is at (5/24,f(5/24))=(5/24,8(5/24)35(5/24)2+6).

Step 7 :Therefore, the function is concave down on (,5/24) and concave up on (5/24,). The point of inflection is at (5/24,f(5/24))=(5/24,8(5/24)35(5/24)2+6)

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