The function is .
Apply first derivative with respect to .
Apply second derivative with respect to .
The values of is
.
Test for concavity in the intervals and
, as shown in the below table.
Intervals | \Test value | \ \
Sign of | \
Conclusion | \
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\
| \
Concave upward | \
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\
| \
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Concave downward | \
The function is concave upward in the interval .
Concave down in the interval .
Concave upward in the interval .
Concave down in the interval .