The derivative tells how fast one quantity changes when another changes. Use it to follow a moving particle and a changing cost. Solve related rates with a ladder, a balloon, a filling cone and a shadow. Then find where a function increases or decreases from the sign of its derivative. It covers the first part of the Indian syllabus unit (NCERT, JEE Main) and the matching topics of A-Level, IB and AP.
3 lessons, about 1 h 15 min3 simulations10 problems3 practice questionsPython in every lesson
The derivative is the rate at which changes when changes, and it carries the units of per unit of . An average rate uses two points. The derivative is its limit as the two points meet. It gives the speed of a moving object, the rate at which an area grows with its radius, and a marginal cost.
In a related rates problem, two or more quantities change with time and are tied together by an equation. Differentiate that equation with respect to using the chain rule, and then put in the numbers for the moment you need. The steps are the same for a sliding ladder, an inflating balloon, a filling cone and a moving shadow.
A function is increasing on an interval if its graph rises as you move to the right, and decreasing if it falls. The sign of the derivative tells which. If on an interval, is strictly increasing there. If , it is strictly decreasing. To find the intervals, solve and test the sign of in each gap. A function that only increases or only decreases is called monotonic.
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