FUNCTIONS AND LIMITS 5
Review of unit 1 –functions and limits
Review
1.
a. Using the graphing calculator at meta-calculator.com, graph for 1/(x-1) as noted the limit as x approaches one from the left is negative infinity, it’s also approached from the right side, and the limit is positive infinity. The limit on this is not equal to the limit from the right, so therefore the limit does not exist.
limx→11x-1
1x-1
11-1
10
Answer = ∞; the limit goes to positive infinity.
Thus, the limit of x as x approaches ∞ is ∞.
limx→∞1x
1limx→∞x
Answer = 0
b. Having used the meta-calculator.com graphing the function y=(e^-x)*(sin(x)) is entered in the graphing calculator and shows the following: (The limit is 0)
ddx(exsinx)= limdx→0 fx+dxdx
Using this equation as followed:
-1≤sinx≤1
-e-x≤e-x*sin(x)≤e^(-x)
-1/e^x≤e^(-x)*sin(x)≤1/ex
limx→∞-1ex=0 limx→∞ 1/e^x
limx→∞ e-x*sinx=0
Answer = lim_(x->-infinity) e^x sin(x) = 0
2.
a. limx→-1-f(x)
Answer: The limit is the y coordinate (y = 2) of the red shaded dot as x approaches -1 from the left.
(x = -1, y = 2)
b. limx→-1+f(x)
Answer: The limit is the y coordinate (y = 3) of the unshaded dot as x approaches -1 from the right.
(x = -1, y = 3)
c. limx→-1f(x)
Answer: The limit from 2a (y=2), is not equal to the limit from 2b (y = 3).
d. f(-1)
Answer: The value of the function at x=-1 and that is represented by the y-coordinate of the shaded red dot.
e. limx→2f(x)
Answer: According to the graph the curve shoots up to infinity as x approaches 2. This does not satisfy the Rule 1 in the definition limits, so it is indeterminate.
f. f(2)
Answer: x = 2 is not part of the domain.
g. limx→4f(x)
Answer: The limit as x approaches 4 from the left and from the right, y = 1; the limits are equal. Plotted (4,1)
3. Bx=x2x2+4
a. For x=10, 25/26*1,000,000 is correct and when simplified, it will be $961,538.
b.
References
Meta Calculator, (n.d.) Graphing Calculator. Retrieved from
http://www.meta-calculator.com/online/