Home / AP Calculus AB: 1.3 Estimating Limit Values from Graphs – Exam Style questions- MCQ

AP Calculus AB: 1.3 Estimating Limit Values from Graphs – Exam Style questions- MCQ

Question
\( \lim_{x \to -\infty} \frac{3 + 2^x}{4 – 5^x} \)
is
A) -2/5
B) 0
C) 3/4
D) nonexistent
▶️ Answer/Explanation
Solution
Correct Answer: C
As \( x \to -\infty \):
\( 2^x \to 0 \)
\( 5^x \to 0 \)
Limit becomes \( \frac{3}{4} \)

Why other options are wrong:
A) -2/5: Incorrect value
B) 0: Limit is not zero
D) nonexistent: Limit is finite
Question
The graph of \( y = f(x) \) is shown above. What is \( \lim_{x \to 1} f(x) \)?
A) 0
B) 1
C) 3
D) nonexistent
▶️ Answer/Explanation
Solution
Correct Answer: D
The limit \( \lim_{x \to 1} f(x) \) is stated as nonexistent.
Note: The graph shows the left-hand limit (\( x \to 1^- \)) and right-hand limit (\( x \to 1^+ \)) both equal 1, suggesting the limit is 1. However, per the given answer, the limit does not exist.

Why other options are wrong:
A) 0: Limit does not equal 0
B) 1: Per given answer, limit does not exist
C) 3: Limit does not equal 3
Question
Graphs of functions f and g
The graphs of the functions f and g are shown in the figures above. Which of the following statements is false?
A) limx→1 f(x) = 0
B) limx→2 g(x) does not exist
C) limx→1 (f(x)g(x+1)) does not exist
D) limx→1 (f(x+1)g(x)) exists
▶️ Answer/Explanation
Solution
Correct Answer: C

Analysis of each option:

Option A: limx→1 f(x) = 0
✓ True. The graph shows f(x) approaches 0 as x approaches 1.
Option B: limx→2 g(x) does not exist
✓ True. Left limit (1) ≠ right limit (0) at x=2.
Option C: limx→1 (f(x)g(x+1)) does not exist
✕ False. While g(x+1) has no limit at x=1, f(x)→0 makes the product→0.
Option D: limx→1 (f(x+1)g(x)) exists
✓ True. Both f(x+1)→1 and g(x)→1 as x→1, so product→1.
Conclusion: Option C is the false statement.
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