Limits
Evaluate \lim_{x \to 0} \frac{x - \sin x}{x - \tan x}, a ratio of two third-order vanishing trigonometric expressions.
Select the correct option:
🔒 Solution Hidden from View
Submit your answer to unlock the detailed step-by-step solution.
More limit, continuity and differentiability Practice Questions
Using L'Hopital's rule or expansion, the limit \lim_{x \to 0} \frac{e^x - 1 - x}{x^2} evaluates to w...
Using L'Hopital's rule or expansion, the limit \lim_{x \to 0} \frac{e^x - 1 - x}{x^2} evaluates to w...
The value of \lim_{x \to 0} \frac{\ln(1 + 2x)}{\sin 3x} is required; choose the correct evaluation u...
The value of \lim_{x \to 0} \frac{\ln(1 + 2x)}{\sin 3x} is required; choose the correct evaluation u...
Evaluate the value of the limit \lim_{x \to 0} \frac{\tan x - \sin x}{x^3}, which arises frequently ...
Evaluate the value of the limit \lim_{x \to 0} \frac{\tan x - \sin x}{x^3}, which arises frequently ...
Determine \lim_{x \to \infty} \left(\frac{x+3}{x-1}\right)^{x+2}, a classic exponential indeterminat...
Determine \lim_{x \to \infty} \left(\frac{x+3}{x-1}\right)^{x+2}, a classic exponential indeterminat...
Find the constants for which \lim_{x \to 0} \frac{a e^x - b \cos x + c e^{-x}}{x \sin x} equals 2, t...
Find the constants for which \lim_{x \to 0} \frac{a e^x - b \cos x + c e^{-x}}{x \sin x} equals 2, t...
Compute the right-hand limit \lim_{x \to 0^+} x^x, a standard 0^0 indeterminate form often tested th...
Compute the right-hand limit \lim_{x \to 0^+} x^x, a standard 0^0 indeterminate form often tested th...
What is the value of \lim_{n \to \infty} \left( \frac{1}{n^2} + \frac{2}{n^2} + \cdots + \frac{n}{n^...
What is the value of \lim_{n \to \infty} \left( \frac{1}{n^2} + \frac{2}{n^2} + \cdots + \frac{n}{n^...
Limit n→∞ of n1[(n+1)(n+2)...(n+n)]1/n is:
Limit n→∞ of n1[(n+1)(n+2)...(n+n)]1/n is:
Let f(x) be a polynomial of degree 4 having extreme values at x=1 and x=2. If $\lim_{x \to 0} ...
Let f(x) be a polynomial of degree 4 having extreme values at x=1 and x=2. If $\lim_{x \to 0} ...
Evaluate the limit: L=limx→0secx−cosxln(1+x+x2)+ln(1−x+x2)
Evaluate the limit: L=limx→0secx−cosxln(1+x+x2)+ln(1−x+x2)
The value of lim(x→∞) (3x² + 2x + 1)/(2x² - x + 3) is
The value of lim(x→∞) (3x² + 2x + 1)/(2x² - x + 3) is
The value of lim(x→0) (sin x)/x is
The value of lim(x→0) (sin x)/x is
Browse all limit, continuity and differentiability questions →
About This Question
- Subject
- mathematics
- Chapter
- limit, continuity and differentiability
- Topic
- limits
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
−21
Both numerator and denominator vanish like x^3 near zero, so the limit is governed by comparing their leading cubic coefficients via Taylor expansion. Using \sin x = x - x^3/6 + \cdots, the numerator x - \sin x = x^3/6 + \cdots. Using \tan x = x + x^3/3 + \cdots, the denominator x - \tan x = -x^3/3 + \cdots. The ratio of leading coefficients is (1/6)/(-1/3) = (1/6) \cdot (-3) = -1/2. Hence the limit is -1/2. Option 1/2 drops the negative sign that arises because x - \tan x is negative for small positive x. Option -2 inverts the coefficient ratio. Option 2 both inverts and loses the sign. The governing JEE pattern is dividing two cubic-order infinitesimals by matching their dominant terms, a technique that hinges on recognising that both expressions are odd functions whose first surviving Taylor terms are cubic. Conceptually, x - \sin x measures how the sine curve lags behind the line y = x, while x - \tan x measures how the tangent curve races ahead of it, so the two corrections point in opposite directions and their ratio inherits a minus sign. Higher-order terms beyond x^3 contribute nothing to the limit because they vanish faster once divided by x^3, which is why retaining only the cubic coefficients is rigorous rather than approximate. Plausibility check: for small positive x, x - \sin x > 0 while x - \tan x < 0, so the quotient must be negative, immediately eliminating the two positive options and supporting the value -1/2 in both sign and magnitude.
This hard difficulty mathematics question is from the chapter limit, continuity and differentiability, covering the topic of limits. It appeared in the 2025 exam.
Looking for more practice? Explore all mathematics questions or browse limit, continuity and differentiability questions on RankGuru.