Chapter 3 Exercises
A. Squeeze Theorem
If −x4≤f(x)≤x4 near zero, find limx→0f(x).
If 2−x2≤g(x)≤2+x2 near zero, find the limit.
Evaluate limx→0x3sin(1/x).
Evaluate limx→0x2cos(7/x).
Evaluate limx→0∣x∣sin(4/x).
Evaluate limx→0xcos(1/x2).
Suppose ∣f(x)∣≤5∣x−2∣. Find limx→2f(x).
Explain why boundedness of f alone is not enough to conclude limx→0f(x)=0.
B. Fundamental sine limits
x→0limxsinx
x→0limxsin(2x)
x→0lim3xsin(7x)
x→0limsin(2x)sin(5x)
x→0limsin(8x)sin(3x)
t→0limtsin(πt)
x→0limsin(4x)x
x→0limsin(5x)3x
C. Tangent and cosine limits
x→0limxtanx
x→0limxtan(4x)
x→0lim2xtan(3x)
x→0limx1−cosx
x→0limx21−cosx
x→0limx21−cos(4x)
x→0limx2sin2x
x→0limx2sin2(3x)
D. Mixed trigonometric limits
x→0limx2sin(2x)sin(3x)
x→0limsin(2x)tan(5x)
x→0limsin2x1−cos(2x)
x→0limxcosxsin(4x)
x→0limx(1+cosx)sinx
x→0limxtanx−sinx
x→0limxsinx1−cosx
x→0limtan(5x)sin(3x)
E. Reasoning and exam practice
Explain why radians are required for limx→0sinx/x=1.
Derive limx→0tanx/x=1 from the sine limit.
Derive limx→0(1−cosx)/x2=1/2.
A student writes sin(5x)=5x. Explain what is wrong and how to use the limit correctly.
Give a squeeze argument for limx→0x4sin(1/x3).
Create a trigonometric limit near zero whose value is 7/4.
Answers begin in the referenced section.
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