ap calculus review: properties of exponents and logarithms<\/a>.<\/p>\nexample 1<\/h4>\n find the absolute minimum and maximum values of <\/p>\n
solution<\/h4>\n the function g<\/em>(x<\/em>) is technically not an exponential function, however it does involve<\/em> an exponential.<\/p>\nlet’s take the first derivative. don’t forget product rule!<\/p>\n
<\/p>\n
find the critical numbers by setting g<\/em> ' equal to 0 and solving. note that because the exponential function itself can never be 0, the only factor that matters here is 1 – 6x<\/em>2<\/sup>.<\/p>\n <\/p>\n
finally, plug the two critical numbers into the original function to determine minimum and maximum. a sketch of the graph also helps to prove that the absolute min and max do occur at those points.<\/p>\n
\ng<\/em>(-0.4082) = -0.2476 (minimum value)<\/li>\ng<\/em>(0.4082) = 0.2476 (maximum value)<\/li>\n<\/ul>\n <\/p>\n
integrating exponential functions<\/h2>\n because the derivative of ex<\/sup><\/em> is equal to ex<\/sup><\/em>, you can expect its antiderivative to be the exact same thing. (but don’t forget the “+ c<\/em>“!)<\/p>\n <\/p>\n
example 2<\/h4>\n let . find the value of c<\/em> guaranteed by the mean value theorem for integrals so that f<\/em>(c<\/em>) is equal to the average value of f<\/em> on the interval [1, 3].<\/p>\nsolution<\/h4>\n we must first find the average value of the function on the given interval. this is a job for an integral. note that there will be a substitution: u<\/em> = 2x<\/em>.<\/p>\n <\/p>\n
next, set f<\/em>(c<\/em>) = 99.01 and solve for c<\/em>.<\/p>\n <\/p>\n
related topics<\/h2>\n the exponential also shows up in a number of applications on the ap calculus exams. <\/p>\n
exponential growth models<\/h3>\n any situation in which the rate of growth is proportional to the amount present lends itself directly to an exponential model.<\/p>\n
the differential equation y<\/em> ' = ky<\/em>, where k<\/em> is a constant, has the general solution, y<\/em> = aekx<\/sup><\/em>. here, the value of the constant a<\/em> is equal to the initial population<\/em>, y<\/em>(0).<\/p>\nexample 3<\/h4>\n a certain bacteria culture has 1000 cells initially. <\/p>\n
the amount x<\/em>, in grams, of a radioactive isotope decays according to the equation dx<\/em>\/dt<\/em> = -0.03x<\/em>, where time t<\/em> is measured in days. determine the half-life<\/em> of the isotope to the nearest day. (note: the half-life<\/strong> of a substance is the amount of time it takes for exactly one-half of the substance to decay.)<\/p>\nsolution<\/h4>\n first, we can build the exponential model (aekx<\/sup><\/em>) based on the given information. here, the initial amount is a<\/em> = 1000, and the decay constant is k<\/em> = -0.03. so, the appropriate exponential model would be:<\/p>\n <\/p>\n
next, to find the half-life, we set x<\/em>(t<\/em>) = 500 (because that’s half of 1000), and solve for t<\/em>.<\/p>\n <\/p>\n
thus the half-life is about 21 days.<\/p>\n
the logistics growth model<\/h3>\n the logistics growth model<\/strong> is an equation the models population growth up to a constant carrying capacity<\/strong> m<\/em>.<\/p>\nthe logistics growth model shows how populations might grow under limited resources.<\/figcaption><\/figure>\nthe natural exponential ex<\/sup><\/em> makes an appearance as part of the solution to the logistics differential equation.<\/p>\n <\/p>\n
for more information and examples, check out: ap calculus bc review: logistics growth model<\/a>.<\/p>\nthe maclaurin series for ex<\/sup><\/em><\/h3>\ntaylor and maclaurin series only show up on the ap calculus bc exam. you should probably memorize the maclaurin series<\/strong> for the natural exponential function.<\/p>\n <\/p>\n
example 4<\/h4>\n find a power series expansion for .<\/p>\n
solution<\/h4>\n we just have to work with the maclaurin series for the natural exponential. i’ve color coded certain parts to make it a little easier to follow.<\/p>\n
<\/p>\n
summary<\/h2>\n\nexponential functions have the basic form f<\/em>(x<\/em>) = ax<\/sup><\/em>, where a<\/em> > 0 is a constant. but the graph can be scaled or shifted by including appropriate coefficients and constant terms.<\/li>\nthe derivative of ex<\/sup><\/em> is equal to ex<\/sup><\/em>. the derivative of ax<\/sup><\/em> is ax<\/sup><\/em> ln a<\/em>.<\/li>\nthe antiderivative (integral) of ex<\/sup><\/em> is equal to ex<\/sup><\/em> + c<\/em>. the antiderivative of ax<\/sup><\/em> is ax<\/sup><\/em> \/ (ln a<\/em>) + c<\/em>.<\/li>\nthe general solution of the differential equation y<\/em> ' = ky<\/em> is the exponential function, y<\/em> = aekx<\/sup><\/em>. <\/li>\nthe solution to the logistics growth model equation also involves exponentials.<\/li>\n the maclaurin series (power series) of the natural exponential function is: \n \n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"exponential functions show up on both the ap calculus ab and bc exams. here’s what you should know about them for the test!<\/p>\n","protected":false},"author":223,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[240],"tags":[241],"ppma_author":[24932],"acf":[],"yoast_head":"\n
ap calculus review: exponential functions - magoosh blog | high school<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n