Finding the Value of a Derivative with Given Function and Derivative Values

In summary, the problem asks to find the value of the derivative of the product of two differentiable functions u and v at x=1, given the values of u and v and their respective derivatives at the same point. Using the formula for the derivative of a product, the result is obtained by plugging in the given values and evaluating at x=1, resulting in a value of -53.
  • #1
carlarae
5
0

Homework Statement


Suppose u and v are differentiable functions of x. Use the given values of the functions and their derivatives to find the value of the indicated derivative.
u(1)=2, u'(1)=-7, v(1)=7,v'(1)=-2
d/dx (uv) at x =1


Homework Equations





The Attempt at a Solution

 
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  • #2
What have you tried?
 
  • #3
Hint

Homework Equations


look for the equations you use when you have to differentiate a combination of two functions... one of them looks like your problem.
 
  • #4
I get d/x(uv)=(2)(-2) + (7)(-7) = -53 but I'm not applying the 1 anywhere that I know of here. as in u(1), does anyone have an example that could help me?
 
  • #5
carlarae said:
I get d/x(uv)=(2)(-2) + (7)(-7) = -53 but I'm not applying the 1 anywhere that I know of here. as in u(1), does anyone have an example that could help me?

In your answer (2)(2) + (7)(-7), where did the 2 come from? What about the -2? Where did you get the 7? Ditto for the -7.

RGV
 
  • #6
That answer looks correct to me. You are applying the 1. The equation for the derivative of the product of two functions is u*v' + v*u'. In your case, you have u(1)*v'(1) + v(1)*u'(1) = (2)(-2) + (7)(-7) = -53. This is d/dx(uv) evaluated at x=1.
 

What is a differentiable function of x?

A differentiable function of x is a mathematical function that is continuous and smooth, with no abrupt changes or discontinuities. This means that the function has a well-defined derivative at every point within its domain.

How do you know if a function is differentiable at a specific point?

A function is differentiable at a specific point if the limit of the difference quotient (slope of the tangent line) exists at that point. This means that the function must be continuous and have a well-defined derivative at that point.

What is the difference between a differentiable function and a non-differentiable function?

A differentiable function is continuous and has a well-defined derivative at every point within its domain. A non-differentiable function, on the other hand, may have abrupt changes or discontinuities, making it not smooth and not having a well-defined derivative at certain points.

Can a function be differentiable but not continuous?

No, a function cannot be differentiable but not continuous. Differentiability implies continuity, as a function must be continuous for the limit of the difference quotient to exist at every point within its domain.

What is the importance of differentiable functions in mathematics and science?

Differentiable functions are important in mathematics and science because they allow us to model and analyze real-world phenomena. They also play a crucial role in calculus, as the derivative of a function is used to find the rate of change, critical points, and optimization in various applications.

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