JEE doubts
500 doubts found
When do I use d = |ax₀+by₀+c|/√(a²+b²) in Straight Lines, and what does it mean?
distance from a point to a line.
When do I use y² = 4ax in Conic Sections, and what does it mean?
standard parabola opening rightward.
How is Limits & Continuity tested in JEE, and what should I focus on?
Prioritise the core ideas: Limit, Continuity, Standard limit.
When do I use dy/dx = dy/du · du/dx in Differentiation, and what does it mean?
the chain rule for composite functions.
When do I use ∫(1/x) dx = ln|x| + C in Integration, and what does it mean?
the integral of 1/x.
When do I use P(A|B) = P(A∩B)/P(B) in Probability, and what does it mean?
conditional probability.
When do I use |a×b| = |a||b|sinθ in Vectors & 3D Geometry, and what does it mean?
magnitude of the cross product (vector).
How is Quadratic Equations tested in JEE, and what should I focus on?
Prioritise the core ideas: Discriminant, Sum and product of roots, Nature of roots.
How is Complex Numbers tested in JEE, and what should I focus on?
Prioritise the core ideas: The imaginary unit, Modulus and conjugate, Argand plane.
When do I use S∞ = a/(1−r) in Sequences & Series, and what does it mean?
sum of an infinite geometric series.
How is Permutations & Combinations tested in JEE, and what should I focus on?
Prioritise the core ideas: Permutation, Combination, Fundamental principle of counting.
How do I revise Binomial Theorem quickly before the exam?
One-page summary of Binomial expansion, General term, Middle term, then timed previous-year questions.
How is Trigonometry tested in JEE, and what should I focus on?
Prioritise the core ideas: Pythagorean identity, Radians vs degrees, Range of sine and cosine.
How is Straight Lines tested in JEE, and what should I focus on?
Prioritise the core ideas: Slope, Perpendicular and parallel lines, Equation forms.
How is Conic Sections tested in JEE, and what should I focus on?
Prioritise the core ideas: Eccentricity, Focus and directrix, Standard equations.
What are the most common mistakes students make in Limits & Continuity?
that's only true when f is continuous at a; limits can exist where the function is undefined.
How is Differentiation tested in JEE, and what should I focus on?
Prioritise the core ideas: Derivative, Chain rule, Product and quotient rules.
How is Integration tested in JEE, and what should I focus on?
Prioritise the core ideas: Antiderivative, Definite integral, Methods of integration.
How is Probability tested in JEE, and what should I focus on?
Prioritise the core ideas: Basic probability, Independent vs mutually exclusive, Conditional probability.
How is Vectors & 3D Geometry tested in JEE, and what should I focus on?
Prioritise the core ideas: Dot product, Cross product, Direction ratios.
What are the most common mistakes students make in Quadratic Equations?
a negative discriminant gives two complex conjugate roots, not 'no roots'.
What are the most common mistakes students make in Complex Numbers?
the product rule for surds doesn't hold for negatives; i·i = i² = −1.
How is Sequences & Series tested in JEE, and what should I focus on?
Prioritise the core ideas: Arithmetic progression, Geometric progression, Infinite geometric series.
What are the most common mistakes students make in Permutations & Combinations?
if rearranging the same items doesn't create a new outcome, use combinations, not permutations.