The five problems above represent just a small sampling of what you’ll find on an AP Calculus AB or BC exam. At what value of x is the slope of the tangent line to g( x) equal to 3? SolutionĪgain, the slope of the tangent line is equal to a derivative value. You’ll need both the Product and Chain Rules for this one. Therefore this function has no inflection points. Use Quotient Rule to help find the second derivative.Īfter simplification, we find that the second derivative is never equal to 0 and never undefined. Don’t forget to rewrite your radical as a power and use Chain Rule. Of course, you must take the first derivative first. You can find inflection points by taking the second derivative. Problem 3įind all inflection points of the curve defined by. V( t) = x '( t) = cos( cos( 4 t ) ) ( -sin( 4 t ) ) (4)Īt time t = π/8, the velocity is equal to: Be careful - we need two applications of the Chain Rule for this one! Findįind velocity by taking the derivative of the position function. The position of a particle moving along the x-axis at time t is x( t) = sin( cos( 4 t ) ), for 0 ≤ t ≤ π. Then you can find the slope and the equation of the tangent line. Here, we have to use the Power Rule and Sum/Difference Rule. To find a tangent line, first take the derivative. Problem 1įind The tangent line to the curve f( x) = x 4 + 3 x – 10 at the point (1, -6). Now let’s take a look at a few problems involving common derivatives that are modeled after actual AP Calculus problems. Derivative of g of x to the n is n g of x to the n-1 times g prime of x.Derivatives of inverse trigonometric functionsĬheck out Calculus Review: Derivative Rules and Derivatives on the AP Calculus AB & BC Exams: A Refresher for more. So don't forget the general power rule is just a specific special case of the chain rule. That's negative 42 x squared oops minus because I have to distribute the negative 7 over these 2 terms so negative 7 times 3 is negative 21 and that's my answer. And in the numerator I'll have negative 7 times 6x squared plus 3. So I have a fraction and I'll have 2x cubed plus 3x-1 to the eighth power. And so let's make the observation that this quantity here because I have a negative 8 exponent it's going to end up in the denominator. So according to this rule h prime is going to be the derivative of this and so I take this n the exponent pull out in front so I get negative 7 times this quantity 2x cubed plus 3x-1.Īnd the new exponent is going to be the old exponent minus 1, so negative 7-1 is negative 8 times and then the derivative of the inside function and that's going to be 6x squared plus 3 I'll put that here and your teacher may want you to simplify this. So this is the inside function, so equals and the outside function is the raising to the negative 7 that's the outside function and inside I'll make blue 2x cubed plus 3x-1. Like if I were going to plug 5 into this function I'd raise 5 to the third power multiply by 2 add 3 times 5, I'd be working on this part of the function. Usually the best way to identify inside versus outside is to think about calculating values. And so just to be absolutely clear I'm going to color code this function so that we can see what's the inside function and what's the outside function. This is just a special case of the chain rule, so let's try it out on this function h of x equals this function 2x cubed plus 3x-1 all raised to the negative 7 power. So the derivative of g of x to the n is n times g of x to the n minus 1 times the derivative of g of x. So how do you differentiate one these well we're going to use a version of the chain rule that I'm calling the general power rule. Anyway this is the chain rule I want to introduce you to what I'm calling a general power function so h of x is the general power function if it could be written as some function g of x any function raised to the nth power. We'll get into that in a second, the call with the chain rule is it's a method for differentiating composite functions like f of g of x and I've been in a habit of color coding my composite functions so that the inside part is blue and the outside part is red. Because it's so tough I've divided up the chain rule to a bunch of sort of sub-topics and I want to deal with a bunch of special cases of the chain rule, and this one is going to be called the general power rule. The chain rule is one of the toughest topics in Calculus and so don't feel bad if you're having trouble with it.
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