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Continuity & Differentiability · Question 35 of 125

Question 35

EasyOriginal question

f(x)=sin⁡xx+cos⁡xf(x) = \frac{\sin x}{x} + \cos x for x≠0x \ne 0, and the value of ff at x=0x = 0 is kk. For which kk is ff continuous at x=0x = 0?

Options for question 35

Show the answer and explanation
CorrectNot quiteAnswer C

Correct answer: C

Explanation

  1. As x→0x \to 0, sin⁡xx→1\frac{\sin x}{x} \to 1 and cos⁡x→cos⁡0=1\cos x \to \cos 0 = 1.

  2. The limit is 1+1=21 + 1 = 2, so k=2k = 2.

Worth noting

1 keeps only one of the two limits; each of sin⁡xx\frac{\sin x}{x} and cos⁡x\cos x tends to 1.

Concept
A constant from a limit
Typical time
60 s
Your time
—
The rule this testsChoosing a constant for continuity
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Ten questions from Continuity & Differentiability, at your own pace.

Practise this chapter →

Ten questions from Continuity & Differentiability, at your own pace.