Solution
Related Formula
For a function to be continuous at a boundary point x = x₀, the left-hand limit, right-hand limit, and exact function value must all match:
x → x₀^- f(x) = x → x₀^+ f(x) = f(x₀)Core Logic
Let's enforce continuity at the critical boundaries, x = 1 and x = 0:
- Continuity at x = 1:
Equating both configurations: 3 + c = 3 c = 0.
- Continuity at x = 0:
Using the Taylor expansion (2h) = 1 - (4h²)/(2!) + (16h⁴)/(4!) - = 1 - 2h² + (2)/(3)h⁴ -
h → 0 (a - b(1 - 2h² + (2)/(3)h⁴ - ))/(h²) = h → 0 ((a-b) + 2bh² - (2)/(3)bh⁴ + )/(h²)For the limit to exist and remain finite, the constant term must vanish: a - b = 0 a = b. The value of the limit is then equal to 2b. To satisfy continuity: 2b = 2 b = 1 a = 1.
Step 1: Checking Differentiability at x = 0
Evaluating the Left-Hand Derivative (LHD) at x = 0 using values a=1, b=1:
LHD = h → 0 (f(-h) - f(0))/(-h) = h → 0 ((1 - (2h))/(h²) - 2)/(-h) LHD = h → 0 ((2 - (2)/(3)h² + ) - 2)/(-h) = h → 0 (2)/(3)h = 0Evaluating the Right-Hand Derivative (RHD) at x = 0:
RHD = h → 0 (f(h) - f(0))/(h) = h → 0 ((h² + 2) - 2)/(h) = h → 0 h = 0Since LHD = RHD = 0, the function is fully differentiable at x = 0.
Step 2: Checking Differentiability at x = 1
Evaluating derivatives at x = 1 with parameter c = 0:
- For 0 ≤ x ≤ 1, f(x) = x² + 2 f'(x) = 2x f'(1^-) = 2.
- For x > 1, f(x) = 2x + 1 f'(x) = 2 f'(1^+) = 2.
Since the left derivative equals the right derivative at x = 1, the function is differentiable at x = 1.
Thus, the function is differentiable everywhere, giving m = 0 points of non-differentiability.
Step 3: Finding the Requested Evaluation Sum
Now substitute the values m=0, a=1, b=1, c=0 into the target equation:
m + a + b + c = 0 + 1 + 1 + 0 = 2Pattern Recognition
Sees: Continuity conditions paired with rational surd trigonometric expansion. Shortcut: When tracking indeterminate limits like (a-b 2x)/(x²), matching expansions row by row prevents typical computation errors encountered with standard L'Hopital differentiation loops.
Chapter Mix
Class 12 Mathematics: Limits, Continuity and Differentiability