First find all possible rational roots. To do this, find all the factors of the lowest order coefficient and the highest order coefficient. For #1, the highest order coefficient is 1 because the x^3 doesn't have a number in front of it. The lowest order coefficient is 30.
Here are all the factors:
Factors of 1 are: 1
Factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30
Now divide each factor of 30 (positive and negative), and divide them by each factor of 1.
Now we perform synthetic division like you have started to do. Try dividing the polynomial by each possible root. If the result has a remainder, that possible root does NOT work. Try another possible root. If there is not a remainder, you have found one of the roots.
For example, when dividing x^3 - 4x^2 -11x + 30 by the possible root 2, we get x^2 - 2x - 15 without a remainder. That means 2 is a root. From here we can factor the result to (x-5)(x+3).
In order for the system to have a solution, both graphs must have an intercept to each others. We see in the picture that both graphs are parallel and do not have any interceptions which we don't know the solution to the system.
That means if graphs are parallel and have no interceptions, there are no solutions. The system of equations are for finding the interceptions of both graphs. But of course! Parallel lines do not intercept.
