If f(x) is increasing, f’(x) is…
+Positive
If f(x) is decreasing, f’(x) is
-negative
f(x) has a critical point if f’(x) is
0 or undefined
f(x) has a relative max if f’(x) is
0(CP) and changes from pos to neg
f(x) has a relative max if f”(x) is
-negative (as long as f’ is 0)
f(x) has a relative min if f’(x) is
0, changing from -to+
f(x) has a relative min if f”(x) is
+positive when f’ is 0
f(x) has an inflection point if f’ has
a MAX/inc→dec ORRR a MIN/dec→inc
f(x) has an inflection point if f” is
0 and is going from +→- OR -→+
f(x) is concave up if f’ is
increasing
f(x) is concave up if f” is
+positive
f(x) is concave down if f’ is
decreasing
f(x) is concave down if f” is
-negative
extreme value theorem
if f is continuous on an interval, there is a guaranteed to be an absolute maximum and minimum
mean value theorem
if f is continuous and differentiable on an interval [a,b] then there is at least one number x=c in (a,b) where f’( c ) = AROC
IROC=AROC at least once if it’s continuous and differentiable
how to find if a function is inc/dec
find when f’(x)=0, make a sign chart, sample points to find the sign between the zeros, justify (f is inc cuz f’ is + or vice versa)
To identify relative extreme use the first derivative test which is…
find the derivative, find the 0s of the derivative, determine if it’s going + to - or - to +, min if -+ and max if +-
identifying absolute extrema, use candidates test which is…
find all critical points, list all critical points and ENDPOINTS in a table, evaluate the function f(x) at these points and select answer as the xvals with the greatest/lowest yvals
second derivative test is…
if f’(a) = 0 and f”(a) is +, then f(x) has a relative min at x=a
if f’(a) = 0 and f”(a) is -, then f(x) has a relative max at x=a
first derivative HAS to be 0 (not undefined)