Sun The sun is the center of the solar system, it is a star, a hot ball of glowing gases. Supply To furnish organs, tissues or cells with a vital element as blood or never fibers. Support To keep going, to uphold. Surroundings The circumstances, conditions or objects by which one is surrounded.
1. Solving Differential Equations (DEs). A differential equation (or DE) contains derivatives or differentials. Our task is to solve the differential equation. This will involve integration at some point, and we'll (mostly) end up with an expression along the lines of  y = ....
A system of equations is a set of equations that are solved collectively (together). The basic linear system is composed of two linear equations with two variables. Remember that linear equations are equations that represent straight lines when graphed. The term simultaneous equations is also used for systems of equations.