JEE · Maths doubts
167 doubts found
I keep getting “Chain rule” questions wrong in Differentiation. What's the trap?
forgetting to multiply by the inner derivative.
I keep getting “Definite integral” questions wrong in Integration. What's the trap?
ignoring that area below the x-axis counts as negative.
I keep getting “Independent vs mutually exclusive” questions wrong in Probability. What's the trap?
treating mutually exclusive events as independent.
I keep getting “Cross product” questions wrong in Vectors & 3D Geometry. What's the trap?
expecting the cross product to be a scalar.
What does “Nature of roots” actually mean in Quadratic Equations, and why does it matter for JEE?
the sign of the discriminant decides whether roots are real, equal, or complex.
What does “Argand plane” actually mean in Complex Numbers, and why does it matter for JEE?
a complex number a+bi is a point (a, b), turning algebra into geometry.
What does “Infinite geometric series” actually mean in Sequences & Series, and why does it matter for JEE?
an infinite GP has a finite sum a/(1−r) only when |r| < 1.
What does “Fundamental principle of counting” actually mean in Permutations & Combinations, and why does it matter for JEE?
if one task has m ways and another n ways, together they have m×n ways.
What does “Middle term” actually mean in Binomial Theorem, and why does it matter for JEE?
for even n there is one middle term; for odd n there are two.
What does “Range of sine and cosine” actually mean in Trigonometry, and why does it matter for JEE?
sinθ and cosθ always lie between −1 and 1.
What does “Equation forms” actually mean in Straight Lines, and why does it matter for JEE?
slope-intercept y=mx+c, point-slope y−y₁=m(x−x₁), and two-point forms describe the same line.
What does “Standard equations” actually mean in Conic Sections, and why does it matter for JEE?
circle (x−h)²+(y−k)²=r² and parabola y²=4ax are the building blocks.
What does “Standard limit” actually mean in Limits & Continuity, and why does it matter for JEE?
lim(x→0) sin x / x = 1 is a key result used everywhere.
What does “Product and quotient rules” actually mean in Differentiation, and why does it matter for JEE?
the derivative of a product is u'v+uv'; of a quotient is (u'v−uv')/v².
What does “Methods of integration” actually mean in Integration, and why does it matter for JEE?
substitution, integration by parts, and partial fractions handle most integrals.
What does “Conditional probability” actually mean in Probability, and why does it matter for JEE?
P(A|B) is the probability of A given that B has occurred, equal to P(A∩B)/P(B).
What does “Direction ratios” actually mean in Vectors & 3D Geometry, and why does it matter for JEE?
the components that fix a line's or vector's direction in 3D space.
I keep getting “Nature of roots” questions wrong in Quadratic Equations. What's the trap?
solving fully when you only need the nature of the roots.
I keep getting “Argand plane” questions wrong in Complex Numbers. What's the trap?
plotting the imaginary part on the x-axis.
I keep getting “Infinite geometric series” questions wrong in Sequences & Series. What's the trap?
applying the sum formula when |r| ≥ 1.
I keep getting “Fundamental principle of counting” questions wrong in Permutations & Combinations. What's the trap?
adding when you should multiply independent choices.
I keep getting “Middle term” questions wrong in Binomial Theorem. What's the trap?
assuming there's always exactly one middle term.
I keep getting “Range of sine and cosine” questions wrong in Trigonometry. What's the trap?
accepting an answer where sinθ > 1.
I keep getting “Equation forms” questions wrong in Straight Lines. What's the trap?
picking a form that doesn't match the given data.