Maths · Class 12 · Chapter 9
Differential Equations
9 lessons 65 min 2 simulations
A differential equation links an unknown function with its derivatives. Instead of giving y directly, it says how fast y changes, and the task is to recover y from that rule. This chapter defines the order and degree of such equations, separates general solutions (with arbitrary constants) from particular ones, and solves three kinds of first-order, first-degree equations: those whose variables separate, homogeneous equations, and linear equations. Growth of money, cooling of a drink and the shape of a curve with a given slope all fit these forms.
What the exam asks
JEE Main questions on this chapter are mostly quick: the order and degree of a given equation, recognising which method fits, and solving a separable, homogeneous or linear equation with an initial condition. The linear equation with its integrating factor e^∫P dx is the most used tool. Common losses: finding the degree before clearing radicals, forgetting the constant of integration before using the initial condition, and dividing through by a term without first making the coefficient of dy/dx equal to 1.
Lessons
9 lessons · 65 min
1What a differential equation isNCERT §9.1–9.26 min2Order of a differential equationNCERT §9.2.15 min3Degree of a differential equationNCERT §9.2.26 min4General and particular solutionsNCERT §9.39 min 1 sim5Variables separableNCERT §9.4.16 min6Growth, decay and coolingNCERT §9.4.1 (Example 9, applications)9 min 1 sim7Homogeneous differential equationsNCERT §9.4.26 min8Linear differential equationsNCERT §9.4.37 min9Chapter reviewMust-know facts, traps and formulas11 min