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Mathematics 19 Online
OpenStudy (anonymous):

Help me!

OpenStudy (anonymous):

Find the values of c that satisfy the equation f(b)-f(a)/b-a= f prime(c) in the conclusion of the mean value theorem for the given function and interval. f(x)=9x+9/x [1/9, 9]

OpenStudy (anonymous):

I told you how to find the answer. It is easy.

OpenStudy (anonymous):

Take derivative of f(x) and solve for it equal to 0..

OpenStudy (anonymous):

9-(9/x^2)

OpenStudy (anonymous):

Rolle's Theorem sets the derivative = 0. The Mean Value Theorem locates the slope of a tangent line that is parallel to a secant of given endpoints. In this case,you want to find the slope of the tangent line of the given function at point c that is parallel to the secant line of the given endpoints. Then find the value of c for the given function that gives you the equation of that line.

OpenStudy (anonymous):

can you show me please?

OpenStudy (anonymous):

f(b)-f(a)/b-a is formula for finding the slope of the secant. Your endpoints are 1/9 and 9 (a = 1/9 and b = 9) Substitute those in to the above formula, and that will be the slope of the secant AND the slope of the tangent line at point [c, f(c)] Find f'(x) [you've already found f'(x), I see]. Now substitute c for x: f'(c) = 9c - 9/c^2. That is the slope of the tangent line at point c. Set that equal to the slope of the secant line. 9c - 9/c^2 = slope of tangent line (which you solved for earlier). Now solve for c!

OpenStudy (anonymous):

I'm having difficulty finding the slope of the secant and tangent line

OpenStudy (anonymous):

The slope of the secant is the same as the slope of any line: m = y2 - y1/(x2 - x1) In this case, the slope is given by f(b) - f(a)/(x - a) Since f(x) = 9x + 9/x, f(b) = 9(9) + 9/9 and f(a) = 9(1/9) + 9/(1/9) b - a = 9 = 1/9 Do the math! That is the slope of the secant.

OpenStudy (anonymous):

b - a = 9 - 1/9

OpenStudy (anonymous):

f(b)=82 f(a)=82

OpenStudy (anonymous):

f(b)-f(a)=0

OpenStudy (anonymous):

what am I doing wrong??

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