solve by graphing
3x + 4y = 20
3x + 2y = 8

Question

solve by graphing 
3x + 4y = 20
3x + 2y = 8

unklerhaukus · Answer

can you rearrange those equations to solve for y?

whpalmer4 · Answer

Here's how I do these:

find 2 points for each line.  Substitute x = 0, solve for y.  substitute y = 0, solve for x.  Plot both points and draw a straight line through them.  

Repeat for other line.  Point of intersection is solution.  If lines are parallel, there are no solutions.  If lines are identical, there are infinitely many solutions.

whpalmer4 · Answer

For the first one, $$3(0) + 4y = 20$$$$4y=20$$$$y=5$$so $(0,5)$ is a point on the line.
$$3x+4(0)=20$$$$3x=20$$$$x=20/3$$so $(20/3,0)$ is another point on the line.

whpalmer4 · Answer

Graphing is a nice visual way of seeing the solution, but in some cases it may be hard to determine the answer as exactly as one might like.  I'd say this problem might be an example of that, whereas solving it by elimination or substitution would give you the exact answer.