Linear Equation with Two Variables and Its Graph
Equation of the form `ax+by=c`, where x,y are variables and a,b,c are numbers, is called linear; numbers a adn b are called coefficients near variables, number c is called free member.
Graph of any linear equation `ax+by=c`, where at least one coeffcient doesn't equal zero, is line; if a=0, then line is parallel to the x-axis, if b=0, then it is parallel to th y-axis (see figure to the right).
Example. Draw graph of the equation `2x-3y=-6`.
Graph of this equation is line. To draw line it is sufficiently to know two its points.
If x=0 then `2*0-3y=-6` or y=2. Thus, first point is (0;2).
If y=0 then `2x-3*0=-6` or x=-3. Thus, second point is (-3;0).
Drawing line through these two points, will give graph of the given equation.