Polynomial and rational functions

Practice sheet

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

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  1. Describe the end behavior of f(x)=7x3f(x) = 7x^{ 3 }.
    1. As x→∞x \to \infty, f(x)→∞f(x) \to \infty; as x→−∞x \to -\infty, f(x)→−∞f(x) \to -\infty
    2. As x→±∞x \to \pm\infty, f(x)→∞f(x) \to \infty
    3. As x→∞x \to \infty, f(x)→−∞f(x) \to -\infty; as x→−∞x \to -\infty, f(x)→∞f(x) \to \infty
  2. Describe the end behavior of f(x)=−9x6f(x) = -9x^{ 6 }.
    1. As x→±∞x \to \pm\infty, f(x)→−∞f(x) \to -\infty
    2. As x→±∞x \to \pm\infty, f(x)→∞f(x) \to \infty
    3. As x→∞x \to \infty, f(x)→−∞f(x) \to -\infty; as x→−∞x \to -\infty, f(x)→∞f(x) \to \infty
  3. p(x)=7x2−9x5+9p(x) = 7x^2 - 9x^5 + 9. What is the leading coefficient of pp?
  4. f(x)=5x2−10x+20f(x) = 5x^2 - 10x + 20. What is the xx-coordinate of the vertex?
  5. f(x)=x2+10x+21f(x) = x^2 + 10x + 21. What is the smallest value of f(x)f(x)?
  6. Draw the graph of y=−(x−h)2+6y = -(x - h)^2 + 6 for h=0h = 0: place the vertex and one more point.
  7. Find all the zeros of p(x)=(x−4)(x+2)2p(x) = (x - 4)(x + 2)^2.
  8. p(x)=(x−4)2(x+9)p(x) = (x - 4)^2(x + 9). What does the graph of pp do at x=4x = 4?
    1. It touches the x-axis and turns back
    2. It crosses the x-axis
    3. It does not reach the x-axis
  9. What is the remainder when p(x)=x3−5x+7p(x) = x^3 - 5x + 7 is divided by x−3x - 3?
  10. Is x−3x - 3 a factor of p(x)=x2−7x+12p(x) = x^2 - 7x + 12?
    1. Yes, because p(3)=0p(3) = 0
    2. No, because p(−3)≠0p(-3) \ne 0
    3. Only if dividing p(x)p(x) by x−3x - 3 leaves the remainder 3
  11. For which value of kk is x−2x - 2 a factor of x2+kx+4x^2 + kx + 4?
  12. x=4x = 4 is a zero of p(x)=x3−4x2−1x+4p(x) = x^3 - 4x^2 - 1x + 4. Find all the zeros of pp.