Lesson 7 of 20 · about 17 min

Elimination

Cramer's rule gets hopeless beyond a few unknowns. The method every computer uses instead was written down in China about 2,000 years ago. Subtract multiples of one equation from another until the system is a staircase, then solve from the bottom up. You'll do it by hand on a real problem from that ancient book, and watch the lines move while the answer stays put.