
3-1 (b) Indefinite integrals of logarithmic functions
Point 2 of 12 — Lesson 1: Integration Techniques (Substitution and By Parts) and Definite IntegralsQuestion bank: 9 questions (9 with pictures)
02 3-1 (b) Indefinite integrals of logarithmic functions
Rules
- Since for :
- If is differentiable and :
- .
- .
✍️ Worked examples
Example 2: Find (a) (b) (c) .
Solution:
- (a) .
- (b) .
- (c) The derivative of the denominator is , which is the numerator.
- So the integral is .
Geometric and physical applications
- If the slope of the tangent at any point is , then the curve is , and the point given on the curve fixes .
- If the rate of change is given, then , and the starting value fixes .
✍️ Worked examples
Example 3: The slope of the tangent to a curve at any point is , and the curve passes through . Find its equation.
Solution:
- (for ).
- Substitute : .
- So .
- The curve is .
Example 4: The area of a lamina changes at the rate cm/s, and its area at is cm. Find its area after 10 seconds.
Solution:
- .
- At : , so .
- .
- At : cm.
📝 Question bank for this point
9 questions linked to this point only, 9 of them with pictures.