MTH251
Sample Exam 1
Fall 2018
Name:
Date:

Show all work if full or partial credit is desired. You may use a graphing calculator or Desmos. If Desmos is used, then the device must be in airplane-mode (i.e., no wifi, cellular, or Bluetooth connections). No notes, books or websites allowed.

Part 1 No Calculator

  1. `lim_{x to 2} 3=`
  2. `lim_{x to 5} x=`
  3. `lim_{x to -2} (x^2+3x-4)=`
  4. `lim_{x to 0+} 1/x=`
  5. `lim_{x to 7} (x^2-49)/(x-7)=`
  6. For what values of `x` is `f(x)={(3-(x-1)^2,,x < 1),(x+1,,x >= 1):}` continuous?
    f(x)={(3-(x-1)^2,,x < 1),(x+1,,x >= 1):}
  7. Use the limit definition of the derivative to find the slope of the tangent line to the curve `f(x)=x^2` at `x=-2`.
    1. `f(-2+h)=`
    2. `f(-2+h)-f(4)=`
    3. `(f(-2+h)-f(4))/h=`
    4. `lim_{h to 0}(f(-2+h)-f(-2))/h=`
    5. So, `f'(-2)=`

Part 2 Calculator Allowed

Secants and Tangents

  1. Estimate the slope of the tangent line (rate of change) to `f(x)=1/x` at `x=2` by finding the slopes of the secant lines through the points:
    1. `x=2.1` and `1.9`
    2. `x=2.01` and `1.99`
    3. Use the slopes of the secants to estimate the slope of the tangent line accurate to 2 decimal places.
    4. Sketch a graph of `f(x)` on the interval `[0,4]` along with the tangent line when `x=2`.

Evaluate the following limits.

  1. `lim_{x to 7} (x^2-49)/(x-7)=`
  2. `lim_{x to -3} (2x^2+4x-5)=`
  3. `lim_{x to 2^-} 1/(x-2)=`
  4. `lim_{theta to 0} sin(4theta)/(4theta)=`
  5. `lim_{x to 0} (1+2x)^(1/x)=`
  6. `lim_{x to 0} (x-9)/(sqrt(x)-3)=`
  7. `lim_{x to 0} (sqrt(3x+1)-1)/(2x)=`
  8. `lim_{x to 0} (3/(x^2-x)+1/x)=`
  9. If `f(x)={((x+3)^2-1,,x < -1),(2x-1,,x >= -1):}`
    1. `lim_{x to -1^-}f(x)=`
    2. `lim_{x to -1^+}f(x)=`
    3. `lim_{x to -1}f(x)=`

Continuity

  1. Determine whether `r(x)=(x^2-49)/(x-7)` is continuous at `x=7`. If it is continuous, explain why. Otherwise, explain why it is discontinuous.
  2. Determine whether `p(x)=x^2-14x+49` is continuous at `x=7`. If it is continuous, explain why. Otherwise, explain why it is discontinuous.
  3. Consider the function `f(x)=1/x` on the interval `-1<=x<=1`.
    `f(-1)=-1` and `f(1)=1`, so, is there a value of `c` in `[-1,1]` such that `f(c)=0`? Why or why not?
  4. For what values of `x` is `g(x)=(x-5)/(x+2)` continuous?

The Precise Definition of a Limit

  1. State the Precise Definition of a Limit.
  2. If `f(x)=2x-1`, `a=-1`, and `epsilon=0.01`, then find an appropriate value of `delta`.
  3. If `f(x)=1/2 x+1` and `a=4`, then find `delta` in terms of `epsilon`.

The Derivative at a Point

  1. Use the limit definition of the derivative to find the slope of the tangent line to the curve `f(x)=5x^2` at `x=4`.
    Evaluate each of the following and state your answers in simplest form:
    1. `f(4+h)=`
    2. `f(4+h)-f(4)=`
    3. `(f(4+h)-f(4))/h=`
    4. `lim_{h to 0}(f(4+h)-f(4))/h=`
    5. So, `f'(4)=`
  2. Use the limit definition of the derivative to find the slope of the tangent line to the curve `f(x)=4x^2` at `x=1`.
  3. `f(x)=sqrt(25-x)`. Use the limit definition of the derivative to compute `f'(9)`.

The Derivative Function

  1. Use the limit definition of the derivative to find the derivative function when `f(x)=5/x`.
    Evaluate each of the following and state your answers in simplest form:
    1. `f(x+h)=`
    2. `f(x+h)-f(x)=`
    3. `(f(x+h)-f(x))/h=`
    4. `lim_{h to 0}(f(x+h)-f(x))/h=`
    5. So, `f'(x)=`
  2. Use the limit definition of the derivative to find the derivative function when `f(x)=3x^2`.
  3. `f(x)=sqrt(25-x)`. Use the limit definition of the derivative to find the derivative function `f'(x)`.
  4. `f(x)=x/(1-x^2)`. Use the limit definition of the derivative to find the derivative function `f'(x)`.
  5. `f(x)=1/x`. Use the limit definition of the derivative to find the second derivative function `f''(x)`.