Mathbee CBSE Mathbee · CBSE Class 12 Maths
Class 12 Continuity And Differentiability · Long Answer3 Markscontinuity_parameters

Class 12 Maths · Continuity And Differentiability · Long Answer #125

For f(x)=x²+3x+a when x≤1 and bx+2 when x>1, find a,b for differentiability at 1.

✅ Step-by-Step Solution

Final Answer: a=3,b=5
  1. Continuity requires 1+3+a=b+2, hence b=a+2.
  2. The left slope at 1 is 2·1+3=5; the right slope is b.
  3. Equality gives b=5, then a=b−2=3. These constants also satisfy continuity.
  4. Therefore a=3,b=5.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] Continuity requires 1+3+a=b+2, hence b=a+2.
  • [1 mark] The left slope at 1 is 2·1+3=5; the right slope is b.
  • [1 mark] Equality gives b=5, then a=b−2=3. These constants also satisfy continuity.
  • [0.5 marks] Therefore a=3,b=5.

Master Chapter 5: Continuity And Differentiability

Practise interactive questions, flashcards, visual mind maps, and timed board tests for Continuity And Differentiability.
📘 Chapter Notes & All Exercises 🚀 Open in Interactive Workspace →
← Previous Question
Let f(x)=(e^(1/x)−1)/(e^(1/x)+1) for x≠0, and f(0)=−1. Show…
Next Question →
For f(x)=x−|x−x²| on [−1,1], find every point of discontinuity…

More Practice Questions in Continuity And Differentiability

Related Questions in Continuity And Differentiability