In: Math
f(x) = 10/cos-1(x). Use calculus to determine:
a) all critical values
b) any local extrema
c) any absolute extrema
d) the intervals where f is increasing/decreasing
e) any points of inflection rounded to the thousandths place
f) intervals where f is concave up/down
No interval was specified so I assumed 0<x<2pi
also I didn't get any concavity not sure if I'm right or not.
I got x= pi as the critical value as well as the relative and absolute minimum extrema.
would greatly appreciate some help
Interval must be taken as
as arccos(x) or inverse of cos(x) is defined in domain [-1,1]
with range [0, pi]
as we can not have 0 in denomiantor, therefore x can not be equal to 1, this is the reason .
as arccos(x) and square root of 1-x^2 , both are always positive. therefore f'(x) > 0,
hence no critical root, and f(x) is increasing function in tis domain.
with lowest value when x = -1, that is f(x) = 10/pi = 3.1831.
On solving from calculator :
f''(x) = 0 at x ~=-0.6580
The point of inflection is x = -0.6580.
There is no critical value as f'(x) can not be zero |
hence, there is no local extrema |
Absolute extrema : minimum when x = -1, that is y = 10/pi maximum when x approaches 1, y approaches infinity. |
f is increasing function in its domain that is |
Point of inflection when f''(x) = 0 (in the neighborhood f''(x) changes sign too), or concavity changes. at x = -0.6580 |
function is concave down function is cocave up |
Graph: