24 hours to exam? This page tells you exactly what to focus on, what to skip, and how to manage your time tomorrow.
CBSE Class 12 Mathematics
24 Hours Before the Exam
No time for everything. This guide tells you exactly what to revise, which topics almost certainly appear, what mistakes to avoid, and how to manage your 3 hours in the exam hall.
Focus on These Chapters First
- Integration — definite integration using properties, integration by parts, partial fractions
- Applications of Derivatives — maxima/minima word problems, rate of change
- Differential Equations — variable separable, homogeneous, linear DE
- 3D Geometry — direction cosines, equation of line and plane, distance formula
- Probability — Bayes' theorem, conditional probability, probability distributions
- Matrices & Determinants — finding inverse, solving system of equations using matrix
- Vector Algebra — dot product, cross product, area of triangle/parallelogram
- Linear Programming — graphical method, corner point method
Key Formulas & Facts to Memorise Right Now
- ∫sin x dx = -cos x | ∫cos x dx = sin x | ∫eˣ dx = eˣ | ∫(1/x)dx = ln|x|
- ∫uv dx = u∫v dx - ∫(u' ∫v dx)dx (integration by parts — ILATE rule)
- Definite integral property: ∫₀ᵃ f(x)dx = ∫₀ᵃ f(a-x)dx
- Bayes' theorem: P(A|B) = P(B|A)×P(A) / P(B)
- Direction cosines: l² + m² + n² = 1 | l = cosα, m = cosβ, n = cosγ
- Cross product: |a×b| = |a||b|sinθ (gives area of parallelogram)
- Dot product: a·b = |a||b|cosθ (gives angle between vectors)
- Linear DE: dy/dx + Py = Q | IF = e^∫P dx | Solution: y × IF = ∫Q × IF dx
Timing Strategy for 3 hours Exam
- 1First 15 min: Read paper — mark questions by difficulty (easy/medium/hard)
- 20–30 min: Section A MCQs and assertion-reason — instinct-based, don't overthink
- 330–80 min: 2-mark and 3-mark — show full working, even for simple steps
- 480–150 min: 5-mark — integration, differential equations, 3D geometry, LP
- 5150–170 min: Case study — usually application-based calculus or probability
- 6Last 10 min: Check +C, limits, and sign errors in differentiation
Common Mistakes — Avoid These Tomorrow
- ✕Forgetting + C (constant of integration) in indefinite integrals
- ✕Using wrong limits in definite integration — double-check lower and upper bounds
- ✕Not checking the second derivative to confirm maxima vs minima
- ✕Writing |a×b| for area of triangle instead of ½|a×b|
- ✕Not converting the DE to standard form before finding integrating factor
- ✕Forgetting to verify the feasibility of corner points in linear programming
- ✕Confusing row operations in matrix — always write the operation being applied
Must Attempt — Never Leave These Blank
- ✓Linear Programming — graphical method is straightforward, guaranteed marks
- ✓Probability — Bayes' theorem and conditional probability follow a fixed pattern
- ✓Matrix inverse and system of equations — follow the algorithm step by step
- ✓Vector dot/cross product problems — formula substitution gives full marks
Skip If Unsure (Return If Time Permits)
- →Complex integration by parts if you're unsure which part is u and which is v
- →Lengthy 3D geometry problems — attempt shorter questions first
Remember: Partial marks exist. Attempt and leave if stuck — come back if time allows. Never spend more than 8 minutes on a single 5-mark question.
Class 12 Maths rewards methodical thinking. Write every step even when it feels obvious — partial marking means you get credit for correct working even if the final answer is wrong.
Night Before — Non-Academic Checklist
Pack your bag
Admit card, 2 pens, pencil, eraser, ruler, geometry box (if needed)
Sleep by 10 PM
Your brain consolidates memory during sleep. Late-night cramming hurts more than it helps
Stop studying at 9 PM
Whatever you don't know by tonight won't be learnt in an hour. Trust your preparation
Set two alarms
One to wake up, one as a backup. Arrive at the centre 30 minutes before the exam
More resources for Class 12 Mathematics
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