Sophie Alpert

 88 How can you prove that the square root of two is irrational? 30 Probability that a stick randomly broken in two places can form a triangle 27 Combinations of selecting $n$ objects with $k$ different types 26 Why is the 2nd derivative written as $\frac{\mathrm d^2y}{\mathrm dx^2}$? 22 Balance chemical equations without trial and error?

### Reputation (3,622)

 +20 Probability that a stick randomly broken in two places can form a triangle +20 How can you prove that the square root of two is irrational? +10 Tiling a $3 \times 2n$ rectangle with dominoes +10 Why is the 2nd derivative written as $\frac{\mathrm d^2y}{\mathrm dx^2}$?

### Questions (9)

 21 Proving Stewart's theorem without trig 19 Tiling a $3 \times 2n$ rectangle with dominoes 17 Finding $\int_0^{\pi/2} \sin x\,dx$ 10 Counting how many hands of cards use all four suits 10 Probability that two people see each other at the coffee shop

### Tags (32)

 113 elementary-number-theory × 3 30 monte-carlo 88 radicals 27 combinatorics × 5 88 rationality-testing 26 derivatives 38 calculus × 3 26 notation 35 probability × 3 25 induction × 2

### Bookmarks (1)

 6 a question related to two competing patterns in coin tossing