18.090 Introduction To Mathematical Reasoning Mit Best

Student learns proof by contrapositive: Prove instead: If ( n ) is odd, then ( n^2 ) is odd. Let ( n = 2m+1 ). Then ( n^2 = 4m^2 + 4m + 1 = 2(2m^2+2m) + 1 ), which is odd. By contrapositive, the original statement holds.

But you will also experience the unique thrill of constructing an ironclad argument from nothing but logic. You will learn to read a theorem and see its skeleton. And when you move on to analysis, topology, or number theory, you will realize that 18.090 gave you the only tool that matters: the ability to reason. 18.090 introduction to mathematical reasoning mit

That "aha" moment—seeing why contrapositive works—is what 18.090 delivers again and again. Student learns proof by contrapositive: Prove instead: If

Why Hammack? It is exceptionally clear, conversational, and filled with graduated exercises. Chapters progress from simple truth tables to the mind-bending proof of the irrationality of ( \sqrt2 ) to the fact that the real numbers are uncountable. Students repeatedly praise the book for its "hand-holding without being condescending." By contrapositive, the original statement holds