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Mathematics 21 Online
OpenStudy (chris215):

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OpenStudy (caozeyuan):

is it b? I am rust on my calc I

OpenStudy (caozeyuan):

have't done those in years

OpenStudy (danjs):

those re in the book in a highlighted box to remember for sure

OpenStudy (solomonzelman):

If f'(x)>0 on interval (a,b) that means the function is increasing on (a,b). Consequentialy, if f''(x)>0, then the slope (f'(x)) is increasing on (a,b).

OpenStudy (solomonzelman):

because f" in relation to f' is same as f' in relation to f. (one way to think about it)

OpenStudy (solomonzelman):

So A would have been true, if it sais "concave up".

OpenStudy (solomonzelman):

[option B] If f '(x) > 0 on the interval (a, b) then f(x) is increasing on the interval (a, b). The slope is greater than zero, so yes, the function is increasing on that interval.

OpenStudy (danjs):

just remember, the derivative is just a instantaneous rate of change, the slope of a tangent line to a curve... that should work

OpenStudy (danjs):

+ derivative, the function has positive sloped tangents, it must be going upwards

OpenStudy (solomonzelman):

If f '(c) = 0, then x = c is a relative maximum on the graph of f(x). Not necessarily! Could be absolute minumum for example.

OpenStudy (danjs):

is that most of calc, how the heck do you calculate a slope of a line with 1 point

OpenStudy (solomonzelman):

What do you realy mean?

OpenStudy (danjs):

infinitesmals i guess a distance vanashing, so really you have a slope from one point, maybe

OpenStudy (solomonzelman):

(If I am interpreting the question correctly, if not nvm) We are considering the case in option C as given.

OpenStudy (solomonzelman):

If you have any questions ask them piz.

OpenStudy (solomonzelman):

Oops, "pliz".

jimthompson5910 (jim_thompson5910):

If f '(c) = 0, then the following is possible (only one can happen) * there is a relative min on f(x) at x = c * there is a relative max on f(x) at x = c * there is a saddle point on f(x) at x = c. A saddle point is a place where the tangent line has a slope of 0, but it's not a min or max this is why you have to use the first or second derivative test to figure out if there is an extrema at x = c

OpenStudy (chris215):

thanks!!

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