Subtract 5x from both sides. This leaves us with 2x = 5. Now divide both sides by 2 to isolate x. If you want an improper fraction you can stop at x = . If you want a mixed number you will have x = 2.
The vertex is at coordinates (0, 3). Since this parabola opens vertically, its axis of symmetry is the x=coordinate of the vertex: x = 0. That is the equation of the y-axis.
This is a self-answering question: you solve it by graphing the equations.
<em>The solution is where the lines intersect</em>. The point of intersection of the lines is the point that satisfies all the equations for the lines, hence is a solution to the system. If they do not intersect, there are no solutions. If the lines are coincident, there are an infinite number of solutions.
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The equations can be graphed by any of a number of methods. (My favorite is to let a graphing calculator do it.) The method of choice depends on the coefficients and the form the equations are given in. Methods of graphing are a topic for a more lengthy discussion.