The Joy of X: A Guided Tour of Math, From One to Infinity

Even the most math-phobic readers might forget their dread after just a few pages of Strogatz’s (The Calculus of Friendship) latest. The author, a Cornell professor of applied mathematics, begins with arithmetic, by way of Sesame Street, then explores algebra, geometry, and, finally, the wonders of calculus—all done cheerfully, with many a wry turn of phrase. From addition and subtraction, with a glimpse into negative numbers and “the black art of borrowing,” it’s a quick step into the hardcore detective work of algebra’s search for the unknown x, with algorithms like the quadratic equation, “the Rodney Dangerfield of algebra” (“it don’t get no respect”). Strogatz rhapsodizes over geometry, which he sees as a marriage of logic and intuition that teaches how to build arguments, step by rigorous step, and geometry’s “loosey-goosey” offshoot, topology. Brisk chapters on prime numbers, basic statistics, and probability are all enlightening without being intimidating. Most impressive is Strogatz’s coverage of calculus, the math used to figure out everything from how fast epidemics spread to the trajectory of a curveball. Readers will appreciate this lighthearted and thoroughly entertaining book. Illus. (Oct.)