A matrix whose columns are solutions of y = A(t)y is called a solution matrix. A solution matrix whose columns are linearly independent is called afundamental matrix. SECTION presents a geometric method for dealing with differential equations that has been known for a very long time, but has become particularly useful and important with the . Differential Equations Final Exam Practice Solutions 1. A tank originally contains 10 gal of water with 1/2 lb of salt in solution. Water containing a salt