Saturday, February 13, 2010

F'(x) graph



1. Where is the function, f(x), increasing? Where is it decreasing? How can you tell from this graph? Explain.

-f(x) is increasing when f'(x)>0
-f(x) is decreasing when f'(x)<0>
  • Since this graph is f'(x), it graphs the slope of f(x). As a result, The function is increasing(positive slope) between (-2,0)U(0,2). The function is decreasing(negative slope) between (-∞,-2)U(2,∞).
  • 2. Where is there an extrema? Explain. (There are no endpoints.)

    -There's a possibility of having "critical points" when f'(x)=0
    • There is a local minimum at x=-2, because the slope=0 and it changes from negative to positive.
    • There is a local maximum at x=2, because the slope=0 and it changes from positive to negative.
    • There isn't a critical point at zero, because there isn't a change of signs
    3. Where is the function, f(x), concave up? Where is it concave down? How can you tell from this graph?

    -f(x) is concave up when f''(x)>0
    -f(x) is concave down when f''(x)<0
    • Concave up:(-∞,-1)U(0,1)
    • Concave down:(-1,0)U(1,∞)
    4. Sketch the graph f(x) on a sheet of paper. Which power function could it be? Explain your reasoning.
    • If you were to find the anti derivative of f'(x), f(x) would be an x^5 power function, because f'(x) has 4 slope changes.

    1 comment:

    1. 1. So how did you know that these intervals were where the slope was positive or negative? (which is correct btw.)
      2. at x=0, it IS a critical point, just not an extrema. you min and max are perfect.
      3. again, how can you tell these answers from this particular graph?
      4. yup!

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