The derivative

Practice sheet

Fresh questions from the whole chapter, to do on paper.

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  1. A ball's position is s(t)=4t2+9ts(t) = 4t^2 + 9t meters after tt seconds. Find its average velocity on [0,6][0, 6], in m/s.
  2. s(t)=5t2s(t) = 5t^2. Simplify the average velocity on [3,3+h][3, 3 + h], s(3+h)−s(3)h\dfrac{s(3 + h) - s(3)}{h} for h≠0h \ne 0. Enter an expression in hh.
  3. s(t)=3t2+7ts(t) = 3t^2 + 7t meters. The average velocity on [6,6+h][6, 6 + h] simplifies to 43+3h43 + 3h m/s. Find the instantaneous velocity at t=6t = 6, in m/s.
  4. f(x)=x2+4xf(x) = x^2 + 4x. Use f′(4)=lim⁡h→0f(4+h)−f(4)hf'(4) = \displaystyle\lim_{h \to 0} \dfrac{f(4 + h) - f(4)}{h} to find f′(4)f'(4).
  5. Which expression is f′(2)f'(2)?
    1. lim⁡h→0f(2+h)−f(2)h\displaystyle\lim_{h \to 0} \dfrac{f(2 + h) - f(2)}{h}
    2. lim⁡h→0(f(2+h)−f(2))\displaystyle\lim_{h \to 0} \big(f(2 + h) - f(2)\big)
    3. f(2+1)−f(2)1\dfrac{f(2 + 1) - f(2)}{1}
    4. f(2)f(2)
  6. f(x)=4xf(x) = \dfrac{ 4 }{x}. Use the limit definition to find f′(3)f'(3).
  7. For f(x)=x2f(x) = x^2, f′(x)=2xf'(x) = 2x. Draw the tangent line to the graph at x=1x = 1: place two points on it.
  8. f(1)=2f(1) = 2 and f′(1)=3f'(1) = 3. Write the tangent line to the graph of ff at x=1x = 1: enter the right-hand side of y=…y = \ldots
  9. For f(x)=x3f(x) = x^3, the difference quotient at x=−3x = -3 simplifies to 27+−9h+h227 + -9h + h^2. What is the slope of the tangent line at x=−3x = -3?
  10. Here is the graph of y=f(x)y = f(x). Tap the point of the graph where f′(x)=0f'(x) = 0.
  11. f(x)=3x2+8xf(x) = 3x^2 + 8x. Use f′(x)=lim⁡h→0f(x+h)−f(x)hf'(x) = \displaystyle\lim_{h \to 0} \dfrac{f(x + h) - f(x)}{h} to find f′(x)f'(x).
  12. V(t)V(t) is the volume of water in a tank, in liters, tt minutes after a tap is opened. V′(2)=8V'(2) = 8. What does this mean?
    1. At t=2t = 2 min, the volume is increasing at about 8 liters per minute.
    2. After 2 minutes, the tank holds 8 liters.
    3. In the first 2 minutes, 8 liters flowed in.
    4. It takes 8 minutes to add 2 liters.