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Isabella Moreno
May 18, 2026

Question details

What is the difference between Eulerian and Hamiltonian paths in graph theory?

I am studying graph theory and I keep confusing Eulerian paths with Hamiltonian paths. Can someone clarify the difference?

Eulerian path: A path that uses every edge exactly once.
**Hamiltonian

Discrete MathematicsCombinatorics
1 answer790
Sarah Mitchell
Sarah Mitchell
May 23, 2026

Question details

How can I memorize trigonometric identities without rote memorization?

I have a trig final next week and Im drowning in identities.

Theres like 50 of them:

  • Pythagorean identities
  • Angle addition formulas
  • Double angle formulas
  • Half
TrigonometryExam Help
2 answers1.7k
William Tate
May 17, 2026

Question details

How to find the number of solutions to sin x = x/10 graphically?

This is an IIT-JEE problem that has been bothering me:

Find the number of solutions to the equation sin⁡x=x10\sin x = \frac{x}{10}sinx=10x​ for x∈Rx \in \mathbb{R}x∈R.

I tried solving it analytically but it seems

TrigonometryIIT-JEE Mathematics
1 answer627
Sarah Mitchell
Sarah Mitchell
Jul 15, 2026

Question details

Why does 0 factorial equal 1 instead of 0? Simple proof

I understand that factorial means multiplying down:

5!=5×4×3×2×15! = 5 \times 4 \times 3 \times 2 \times 15!=5×4×3×2×1

and

3!=3×2×1.3! = 3 \times 2 \times 1.3!=3×2×1.

But then I see this:

0!=10! = 10!=1

and it feels wrong.

If there are zero numbers to multiply, why is the

AlgebraCombinatoricsMath MisconceptionsExam HelpProofs
3 answers2.2k
Isabella Moreno
Jun 11, 2026

Question details

How to prove that the derivative of sin x is cos x using the limit definition?

I'm in a calculus class and we proved that ddxsin⁡x=cos⁡x\frac{d}{dx} \sin x = \cos xdxd​sinx=cosx using the limit definition of the derivative:

ddxsin⁡x=lim⁡h→0sin⁡(x+h)−sin⁡xh\frac{d}{dx} \sin x = \lim_{h \to 0} \frac{\sin(x+h) - \sin x}{h}dxd​sinx=h→0lim​hsin(x+h)−sinx​

But the proof uses the identity sin⁡(A+B)=sin⁡Acos⁡B+cos⁡Asin⁡B\sin(A+B) = \sin A \cos B + \cos A \sin Bsin(A+B)=sinAcosB+cosAsinB and then relies on two

Mathematical LogicA-Level Mathematics
1 answer453
Sophia Rossi
Jun 11, 2026

Question details

How to prove that √2 is irrational by contradiction?

I'm preparing for IIT-JEE and I need to understand the classic proof that 2\sqrt{2}2​ is irrational. I've seen the proof but I have some doubts about the logic.

The proof

AlgebraNumber TheoryIIT-JEE MathematicsProofs
2 answers711
Ahmed Al-Rashid
Jun 11, 2026

Question details

For which primes p does x³ + y³ = p z³ admit non-trivial integer solutions?

Consider the Diophantine equation

x3+y3=pz3,x^3 + y^3 = p z^3,x3+y3=pz3,

where ppp is a prime and we seek non-trivial integer solutions (x,y,z)∈Z3∖{(0,0,0)}(x,y,z) \in \mathbb{Z}^3 \setminus \{(0,0,0)\}(x,y,z)∈Z3∖{(0,0,0)}.

By a classical descent argument using the fact that Q(−3)\mathbb{Q}(\sqrt{-3})Q(−3​) has class

Number Theory
1 answer527
Mike Johnson
Mike Johnson
May 1, 2026

Question details

Why is dividing by zero undefined instead of infinity?

In school they told us "you cant divide by zero" but they never explained WHY.

Like if you divide a number by a really small number you get a really

AlgebraInfinity and ParadoxesMath MisconceptionsLimits
2 answers2.6k