The number of real solution(s) of the equation x^2+3x+2=min\|x-3|, |x+2|\ is: [cite: 3396, 3397]

Solution & Explanation

### Related Formula The function min\f(x), g(x)\ chooses the lower vertical path between the two curves at any coordinate x. ### Core Logic Analyze the conditions for the \right-hand function min\|x-3|, |x+2|\: - The intersection of |x-3| = |x+2| happens at x - 3 = -(x + 2) Rightarrow 2x = 1 Rightarrow x = 0.5. - For x le 0.5, |x+2| le |x-3| Rightarrow min = |x+2|. - For x > 0.5, |x-3| le |x+2| Rightarrow min = |x-3|.
Min function intersection graph for Q68 - JEE Main 2025 Evening
Min function intersection graph for Q68 - JEE Main 2025 Evening
### Step 1: Check Interval x le -2 Here, |x+2| = -(x+2) = -x-2: x^2 + 3x + 2 = -x - 2 Rightarrow x^2 + 4x + 4 = 0 (x+2)^2 = 0 Rightarrow x = -2 This is a valid solution as it lies precisely within the interval condition boundary. ### Step 2: Check Interval -2 < x le 0.5 Here, |x+2| = x+2: x^2 + 3x + 2 = x + 2 Rightarrow x^2 + 2x = 0 x(x+2) = 0 Rightarrow x = 0 quad textor quad x = -2 Only x = 0 fits inside this interval. ### Step 3: Check Interval x > 0.5 Here, min = |x-3| = 3-x: x^2 + 3x + 2 = 3 - x Rightarrow x^2 + 4x - 1 = 0 x = frac-4 pm sqrt16 - 4(1)(-1)2 = -2 pm sqrt5 Evaluating values: -2 + sqrt5 approx 0.236, which does not satisfy x > 0.5. Thus, no real roots occur in this span. Combining valid points, we find exactly 2 distinct real solutions (x = -2, 0). ### Pattern Recognition Sketching a rough visualization showing the parabola crossing below the sharp wedge of the combined absolute values makes it visually clear that there are exactly two crossing points, confirming the algebraic count. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Quadratic Equations Class 12 Mathematics: Limits, Continuity and Differentiability

Reference Study Guides

More Limits, Continuity and Differentiability Previous-Year Questions — Page 9

Q17 jee_main_2024_31_jan_morning Continuity Check
Let g(x) be a linear function and f(x) = begincases g(x) & , x le 0 \\ left(frac1+x2+xright)^frac1x & , x > 0 endcases is continuous at x = 0. If f'(1) = f(-1), then the value of g(3) is
  • A. frac13 log_e left(frac49e^1/3right)
  • B. frac13 log_e left(frac49right) + 1
  • C. log_e left(frac49right) - 1
  • D. log_e left(frac49e^1/3right)

Solution

### Core Logic Let g(x) = ax + b. Since f(x) is continuous at x = 0: lim_x to 0^+ f(x) = f(0) lim_x to 0 left(frac1+x2+xright)^frac1x = b As x to 0, the base approaches frac12, and exponent approaches infty. Thus, left(frac12right)^infty = 0. So, b = 0. Thus, g(x) = ax. ### Step 1: Calculate Derivative For x > 0, f(x) = left(frac1+x2+xright)^frac1x. Let y = f(x). ln y = frac1x lnleft(frac1+x2+xright) Differentiating both sides w.r.t x: frac1y y' = -frac1x^2 lnleft(frac1+x2+xright) + frac1x cdot frac2+x1+x cdot frac1(2+x) - (1+x)1(2+x)^2 y' = y left[ -frac1x^2 lnleft(frac1+x2+xright) + frac1x(1+x)(2+x) right] ### Step 2: Apply Condition At x=1, y = f(1) = frac23. f'(1) = frac23 left[ -1 lnleft(frac23right) + frac16 right] = -frac23 lnleft(frac23right) + frac19 Also f(-1) = g(-1) = -a. Given f'(1) = f(-1) implies -a = -frac23 lnleft(frac23right) + frac19. a = frac23 lnleft(frac23right) - frac19 ### Step 3: Evaluate g(3) g(3) = 3a = 2 lnleft(frac23right) - frac13 g(3) = lnleft(frac49right) - frac13 = lnleft(frac49right) - ln(e^1/3) = lnleft(frac49e^1/3right) ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Continuity and Differentiability Class 12 Maths: Application of Derivatives

More Limits, Continuity and Differentiability Questions — jee_main_2025_24_jan_evening

Practice all Limits, Continuity and Differentiability previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)