Let the function f(x) = fracx3 + frac3x + 3, x neq 0 be strictly increasing in (-infty, alpha_1) cup (alpha_2, infty) and strictly decreasing in (alpha_3, alpha_4) cup (alpha_4, alpha_5). Then sum_i=1^5 alpha_i^2 is equal to:

Solution & Explanation

### Related Formula f'(x) > 0 implies textIncreasing f'(x) < 0 implies textDecreasing ### Core Logic Differentiate the rational function and determine the critical intervals by assessing where the derivative flips signs around critical points and domain boundaries. ### Step 1: Derivative Assessment Given f(x) = fracx3 + frac3x + 3 f'(x) = frac13 - frac3x^2 = fracx^2 - 93x^2 Critical points occur at x = pm 3, and a domain discontinuity sits at x = 0. ### Step 2: Sign Scheme Mapping Analyzing interval signs: * Strictly Increasing (f'(x) > 0): x in (-infty, -3) cup (3, infty) * Strictly Decreasing (f'(x) < 0): x in (-3, 0) cup (0, 3) ### Step 3: Interval Summation Comparing bounds with assigned symbols: alpha_1 = -3, quad alpha_2 = 3, quad alpha_3 = -3, quad alpha_4 = 0, quad alpha_5 = 3 sum_i=1^5 alpha_i^2 = (-3)^2 + (3)^2 + (-3)^2 + (0)^2 + (3)^2 = 9 + 9 + 9 + 0 + 9 = 36 ### Pattern Recognition Functions of the form x + frackx always present localized extrema turning symmetric zones at pmsqrtk. Always include the asymptotes (x=0) when stating precise disjoint decreasing intervals. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Application of Derivatives

Reference Study Guides

More Application of Derivatives Previous-Year Questions — Page 4

Q5 jee_main_2024_30_january_evening Maxima and Minima
Let f(x) = (x + 3)^2 (x - 2)^3, x in [-4, 4] . If M and m are the maximum and minimum values of f , respectively in [-4, 4] , then the value of M - m is:
  • A. 600
  • B. 392
  • C. 608
  • D. 108

Solution

### Related Formula textTo find absolute extrema, evaluate f(x) text at critical points and domain boundaries. ### Core Logic Calculate the derivative of f(x) using the product rule: f'(x) = fracddx [(x + 3)^2] cdot (x - 2)^3 + (x + 3)^2 cdot fracddx [(x - 2)^3] f'(x) = 2(x + 3)(x - 2)^3 + 3(x + 3)^2(x - 2)^2 Factor out the common terms (x+3)(x-2)^2: f'(x) = (x + 3)(x - 2)^2 [2(x - 2) + 3(x + 3)] f'(x) = (x + 3)(x - 2)^2 [2x - 4 + 3x + 9] f'(x) = 5(x + 3)(x - 2)^2 (x + 1) Setting f'(x) = 0 gives the critical points: x = -3, -1, 2 ### Step 1: Evaluating at Critical Points and Boundaries Evaluate f(x) at x = -4, -3, -1, 2, 4:
Maxima and Minima diagram for Q5 - JEE Main 2024 Evening
Maxima and Minima diagram for Q5 - JEE Main 2024 Evening
For x = -4: f(-4) = (-4 + 3)^2(-4 - 2)^3 = (1)(-216) = -216 For x = -3: f(-3) = 0 For x = -1: f(-1) = (-1 + 3)^2(-1 - 2)^3 = (4)(-27) = -108 For x = 2: f(2) = 0 For x = 4: f(4) = (4 + 3)^2(4 - 2)^3 = 49 times 8 = 392 ### Step 2: Finding M and m From the evaluated values, the maximum M = 392 and the minimum m = -216. M - m = 392 - (-216) = 392 + 216 = 608 ### Pattern Recognition For polynomials on a closed interval, critical points combined with boundary values reliably expose the absolute max and min. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Application of Derivatives
Q5 jee_main_2024_30_jan_morning Maxima and Minima
The maximum area of a triangle whose one vertex is at (0, 0) and the other two vertices lie on the curve y = -2x^2 + 54 at points (x, y) and (-x, y) where y > 0 is:
  • A. 88
  • B. 122
  • C. 92
  • D. 108

Solution

### Related Formula textArea of Delta = frac12 times textbase times textheight ### Core Logic
Maxima and Minima diagram for Q5 - JEE Main 2024 Morning
Maxima and Minima diagram for Q5 - JEE Main 2024 Morning
The vertices of the triangle are (0, 0), (x, y), and (-x, y). The base of the triangle lies along the horizontal line segment joining (-x, y) and (x, y). Length of base = 2x. The height of the triangle from (0,0) to the line segment is y. So, Area Delta = frac12 (2x) (y) = xy (Assuming x > 0). ### Step 1: Setting up the area function Substitute y = -2x^2 + 54 into the area function: textArea(Delta) = A(x) = x(-2x^2 + 54) = -2x^3 + 54x ### Step 2: Differentiating to find maximum area To find the maximum area, take the derivative with respect to x and set it to zero: A'(x) = fracdAdx = -6x^2 + 54 Setting A'(x) = 0: -6x^2 + 54 = 0 Rightarrow 6x^2 = 54 Rightarrow x^2 = 9 Since x represents half the base length, x = 3. ### Step 3: Calculating maximum area Substitute x = 3 back into the area function: A_textmax = 3(-2(3)^2 + 54) = 3(-18 + 54) = 3(36) = 108 ### Pattern Recognition For symmetric figures inscribed under a parabolic arch, the area function A(x) = x cdot y(x) is standard. Differentiate and find the critical point directly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Application of Derivatives
Q7 jee_main_2024_30_jan_morning Mean Value Theorems
Let g : mathbbR to mathbbR be a non-constant twice differentiable such that g'left(frac12right) = g'left(frac32right). If a real valued function f is defined as f(x) = frac12left[g(x) + g(2 - x)right], then
  • A. f'(x) = 0 for at least two x in (0,2)
  • B. f'(x) = 0 for exactly one x in (0,1)
  • C. f'(x) = 0 for no x in (0,1)
  • D. f^primeleft(frac32right) + f^primeleft(frac12right) = 1

Solution

### Related Formula Rolle's Theorem: If f(x) is continuous on [a, b], differentiable on (a, b), and f(a) = f(b), then there exists at least one c in (a, b) such that f'(c) = 0. ### Core Logic Given f(x) = frac12left[g(x) + g(2 - x)right]. Differentiating f(x) with respect to x: f'(x) = fracg'(x) - g'(2 - x)2 ### Step 1: Evaluating the derivative at given points Evaluate f'left(frac32right): f'left(frac32right) = fracg'left(frac32right) - g'left(frac12right)2 Since g'left(frac12right) = g'left(frac32right), we get: f'left(frac32right) = 0 Also evaluate f'left(frac12right): f'left(frac12right) = fracg'left(frac12right) - g'left(frac32right)2 = 0 Additionally, observe that f'(1) = fracg'(1) - g'(1)2 = 0. ### Step 2: Applying Rolle's Theorem We have f'left(frac12right) = 0, f'(1) = 0, and f'left(frac32right) = 0. By Rolle's Theorem on f'(x) (though we are asked about f'(x)=0 directly), we already found three distinct roots for f'(x) = 0: x = frac12, 1, frac32. Notice that x = 1/2 and x=1 are in (0, 2), and x=3/2 is in (0, 2). Thus f'(x) = 0 for at least three values in (0, 2), which satisfies the condition "at least two x in (0, 2)". ### Pattern Recognition Symmetry in function definition g(x) + g(a-x) guarantees a critical point at x = a/2. Additional critical points arise due to the given condition on g'(x), creating a scenario perfectly suited for Rolle's implications. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Application of Derivatives
Q13 jee_main_2024_31_jan_evening Monotonicity and Distances
If the function f: (-infty, -1] to (a, b] defined by f(x) = e^x^3 - 3x + 1 is one-one and onto, then the distance of the point P(2b + 4, a + 2) from the line x + e^-3y = 4 is :
  • A. 2sqrt1 + mathrme^6
  • B. 4sqrt1 + mathrme^6
  • C. 3sqrt1 + mathrme^6
  • D. sqrt1 + mathrme^6

Solution

### Related Formula textDistance of point (x_1, y_1) text from line Ax+By+C=0 text is d = frac|Ax_1 + By_1 + C|sqrtA^2 + B^2 ### Core Logic
Monotonicity and Distances diagram for Q13 - JEE Main 2024 Evening
Monotonicity and Distances diagram for Q13 - JEE Main 2024 Evening
Given f(x) = e^x^3 - 3x + 1. Check monotonicity on (-infty, -1]: f'(x) = e^x^3 - 3x + 1 cdot (3x^2 - 3) = 3(x-1)(x+1)e^x^3 - 3x + 1 For x le -1, (x+1) le 0 and (x-1) < 0, making f'(x) ge 0. Hence f(x) is strictly increasing. Since f is onto (a,b], the range is dictated by the domain boundaries: a = lim_xto-infty f(x) = e^-infty = 0 b = f(-1) = e^-1 + 3 + 1 = e^3 Point P(2b + 4, a + 2) equiv P(2e^3 + 4, 2). Find distance from line x + e^-3y - 4 = 0: d = frac|2e^3 + 4 + e^-3(2) - 4|sqrt1^2 + (e^-3)^2 = frac2e^3 + 2e^-3sqrt1 + e^-6 d = frac2e^3(1 + e^-6)sqrt1 + e^-6 = 2e^3 sqrt1 + e^-6 = 2sqrte^6 + 1 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Applications of Derivatives Class 11 Maths: Straight Lines
Q22 jee_main_2024_31_jan_morning Maxima and Minima
Let S = (-1, infty) and f : S to mathbbR be defined as f(x) = int_-1^x (e^t - 1)^11 (2t - 1)^5 (t - 2)^7 (t - 3)^12 (2t - 10)^61 dt. Let p = Sum of square of the values of x, where f(x) attains local maxima on S and q = Sum of the values of x, where f(x) attains local minima on S. Then, the value of p^2 + 2q is
Numerical Answer. Answer: 27 to 27

Solution

### Related Formula f'(x) = 0 text for critical points. Change from + to - text means local maxima, - to + text means local minima. ### Core Logic Using Newton-Leibniz formula: f'(x) = (e^x - 1)^11 (2x - 1)^5 (x - 2)^7 (x - 3)^12 (2x - 10)^61 The critical points are roots of f'(x) = 0: x = 0, frac12, 2, 3, 5.
Maxima and Minima diagram for Q22 - JEE Main 2024 Morning
Maxima and Minima diagram for Q22 - JEE Main 2024 Morning
### Step 1: Sign Change Analysis Perform the Wavy Curve Method for x in (-1, infty): At x=5 (odd power 61): sign changes - to + (Local Minima) At x=3 (even power 12): sign doesn't change (Neither) At x=2 (odd power 7): sign changes + to - (Local Maxima) At x=1/2 (odd power 5): sign changes - to + (Local Minima) At x=0 (from e^x - 1, odd power 11): sign changes + to - (Local Maxima) ### Step 2: Compute p and q Local minima at x = 5, frac12. Local maxima at x = 2, 0. p = 0^2 + 2^2 = 4 q = 5 + frac12 = frac112 ### Step 3: Final Computation p^2 + 2q = 16 + 2left(frac112right) = 16 + 11 = 27 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Application of Derivatives Class 12 Maths: Integrals

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