Question

Describe how you can find the number of solutions of two or more

Answer 1

Answer:

Suppose we have a system of two linear equations, this can be written as:

y = a*x + b

y = c*x + d

Now, we have 3 possible cases here.

The solutions of the system are the points where the graphs of the linear equations do intersect.

Then, if for example, we have two parallel lines (two parallel lines never intersect) we have no solutions.

And we know that two lines are parallel if they have the same slope and different y-intercept.

Then the system:

y = a*x + b

y = a*x + c

has no solutions.

If we have both equal lines, then the lines intersect in infinitely many points, meaning that we have infinite solutions, then the system:

y = a*x + b

y = a*x +b

has infinite solutions.

And if the lines intersect only one time we have one solution, and this happens when the slopes are different, so the system:

y = a*x + b

y = c*x + d

has only one solution.

Now, if we have more equations:

y = a*x + b

y = c*x + d

y = k*x + n

We have more equations than variables, then this system only has one solution of the 3 lines intersect at the same point, which is really rare.

One case where we have a solution here is if the 3 equations have the same y-intercept:

y = a*x + b

y = c*x + b

y = d*x + b

where the solution is the point (0, b)

Of course, there are other possible solutions, but these are not as formulaic as this ones.