Find the slope of the function at given value.

Question

f(x)=-3x²+8x-6/x² when x=5

I got the derivative which was -6x+8+12/x^3 and then plugged in x=5, and got -2738/125. Am I correct?

Answer 1

Here is how you can check this using the TI-84 calculator.

Enter in your equation for y= (graph)

Press the graph button

Press 2nd-Trace-#6 (This is dy/dx)

You will press 5, then Enter (for x=5)

The display reads -21.904

When I do the math with your fraction, I get the same thing. Your answer is correct.

Answer 2

Perfect! I'm guessing you might be a little concerned about the algebra and fractions. But, good work!!!