Exercise 2.11 Atiyah-Macdonald
128493
Given a commutative ring $R$ and an epimorphism of free modules $R^m \to R^n$ is then $m \geq n$?
152932
Proof: $\det\pmatrix{\langle v_i , v_j \rangle}\neq0$ $\iff \{v_1,\dots,v_n\}~\text{l.i.}$
19285
simplifying $ (h^2_2-h^2_3)\over ({1\over h_3})-({1\over h_2})$
61526
An exercise about nilpotent quotient groups
89177
$\operatorname{adj}(AB) = \operatorname{adj} B \operatorname{adj} A$
62917
Associated Prime Ideals in a Noetherian Ring; Exercise 6.4 in Matsumura
126094
Hartshorne Algebraic Geometry Exercise II.2.16.
67460
Orientation on $\mathbb{CP}^2$
125474
Exercise 16 from chapter 3 of Stein & Shakarchi's complex analysis
141010
Computing $n$-th external power of standard simplectic form
52517
Construction of $\mathbb{CP}^2$ from $S^2\times S^2$
43350
Schwarz's Lemma exercise
105913
Calculations in quotient rings
133884
A proof using Yoneda lemma
69945
A PDE exercise from Gilbarg Trudinger. problem 2.2
39201
Atiyah-Macdonald, Exercise 5.4
70394
Prove that $a * b$ is a group (Hungerford, 2nd ed., sec $7.2$, Exercise $22$)