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What are all values of x for which the graph of y = x^4 - 6x^2 + x is concave downward? Show your work and justify your answer.

User Infogulch
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Answer:

A function is concave downward if its second derivative is negative. To find the values of x for which the graph of y = x^4 - 6x^2 + x is concave downward, we need to find the values of x for which the second derivative of y is negative.

The second derivative of y = x^4 - 6x^2 + x is y'' = 12x^2 - 12x

To find the values of x for which y'' is negative, we need to find the roots of the equation 12x^2 - 12x = 0.

We can factor the equation as: 12x(x-1) = 0

which gives us x = 0 and x = 1 as the roots.

Now, we need to test the sign of the second derivative in the intervals between the roots.

In the interval (0,1)

y'' = 12x^2 - 12x is positive, therefore the function is not concave downward in this interval.

In the interval (-infinity,0)

y'' = 12x^2 - 12x is negative, therefore the function is concave downward in this interval.

In the interval (1,infinity)

y'' = 12x^2 - 12x is negative, therefore the function is concave downward in this interval.

Therefore, the values of x for which the graph of y = x^4 - 6x^2 + x is concave downward are all values of x less than 0 or greater than 1.

User Qubeuc
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