Problem Bank

A random taste of what’s inside — refresh for a new set.

You’re seeing 12 random problems out of 3678. Create a free account to browse the full bank with topic filters and endless scroll.

7/10

Extrema from an ODE Condition

Let f(x)f(x) satisfy

x2f(x)+2xf(x)=exx,f(2)=e28.x^2f'(x)+2xf(x)=\frac{\mathrm e^x}x,\qquad f(2)=\frac{\mathrm e^2}8.

For x>0x>0, determine, with justification, whether f(x)f(x) has a local maximum and/or a lo…

functionsExtremacalculusMonotonicity
8/10

Zeta Partial Sums

The Riemann zeta function ζ(s)\zeta(s) is closely tied to the distribution of primes. Writing Re(s)\operatorname{Re}(s) for the real part of a complex number ss, define

ψk(s)=\psi_k(s) = …
number theoryModular ArithmeticsequencesEstimation+2
8/10

Angle Inequalities in a Folded Right Triangle

figure

In ABC\triangle ABC, C=90\angle C=90^\circ, AC=1AC=1, BC=3BC=\sqrt{3}, and DD is the midpoint of side ABAB. A point MM lies o…

solid geometryTrigonometric IdentitiesTriangle Geometry
5/10

A Right Angle Inside a Right Triangle

figure

As shown in the figure, in triangle ABCABC we have ABC=90\angle ABC = 90^\circ, AB=3AB = \sqrt{3}, and BC=1BC = 1. The poi…

plane geometryLaw of SinestrigonometryLaw of Cosines
6/10

Lattice Points Near a Line

Find the minimum distance from a lattice point (a point with integer coordinates) to the line

y=53x+45.y = \frac{5}{3}x + \frac{4}{5}.
Diophantine Equationsnumber theoryanalytic geometry
7/10

A Midpoint Locus of Skew Segments

Points AA and BB lie on skew lines aa and bb respectively, and the segment ABAB is perpendicular to both. Moving points PaP\in a and QbQ\in b satisfy that PA+QBPA+QB is constant. …

plane geometryParametrizationsolid geometrySymmetry
8/10

A Constant Slope Combination

The ellipse C:x2a2+y2b2=1C:\dfrac{x^2}{a^2}+\dfrac{y^2}{b^2}=1 (a>b>0a>b>0) has upper vertex A(0,1)A(0,1) and eccentricity 32\dfrac{\sqrt 3}2.

1. Find the equation of the ellipse CC. 2. Let BB be…

Inscribed AngleCirclesconic sections
8/10

A Tangent Intercept Ratio

The inequality

ln(x+1)1ax+b\ln(x + 1) - 1 \leqslant ax + b

holds for all x>1x > -1. Find the minimum value of ba\dfrac{b}{a}.

calculusConvexityLogarithmsinequality
7/10

A Circumcenter on a Line

A moving point QQ in the coordinate plane satisfies QEQF=22|QE| - |QF| = 2\sqrt{2}, where E(3,0)E(-\sqrt{3}, 0) and F(3,0)F(\sqrt{3}, 0).

1. Find the equation of the locus CC of QQ. 2. A li…

Circlesconic sectionsanalytic geometrySymmetry
7/10

A Symmetric Derivative Condition

A function f(x)f(x) is differentiable on R\mathbb{R}, with

f(x)+f(x)=x2for all x,f(x)>xon (0,+).f(-x) + f(x) = x^2 \quad \text{for all } x, \qquad f'(x) > x \quad \text{on } (0, +\infty).

If

f(2a)f(a)\gf(2 - a) - f(a) \g…
functionscalculusMonotonicitySymmetry
6/10

A Geometric Probability

Let f(x)=1x2f(x) = |1 - x^2|. A number aa is chosen uniformly from [0,1][0, 1] and a number bb uniformly from [1,2][1, 2], independently. Find the probability that f(a)f(b)f(a) \leqslant f(b).

probabilityAbsolute ValueCirclesanalytic geometry
7/10

Three Absolute Dominations

Real numbers a,b,ca, b, c satisfy

ab+c,bc+a,ca+b.|a| \geqslant |b + c|, \qquad |b| \geqslant |c + a|, \qquad |c| \geqslant |a + b|.

Prove that a+b+c=0a + b + c = 0.

Absolute ValuealgebrainequalitySymmetry

Sign up to unlock all 3678 problems.