Math Medics
S.o.s. Math: Calculus Integration by Parts
Very nice tutorial explaining integration by parts in calculus. The tutorial explains the formula in detail and then has links to online examples the student can work.
Math Medics
S.o.s. Math: Systems of Equations in Three Variables
It is often desirable or even necessary to use more than one variable to model a situation in many fields. When this is the case, we write and solve a system of equations in order to answer questions about the situation.