Find the sum of all integers 30 to 80. (Is there a formula to do this?
2 answers:
You might be interested in
Try graphing using the x-intercept and y-intercept.
-15x - 5y = 45
Put in x = 0 to get -5y = 45, making y = -9. Point (0, -9) is on the line.
Put in y = 0 to get -15x = 45, making x = -3. Point (-3, 0) is on the line.
-2x + 6y = 6
Put in x = 0 to get 6y = 6, making y = 1. Point (0, 1) is on the line.
Put in y = 0 to get -2x = 6, making x = -3. Point (-3, 0) is on the line.
(We've actually stumbled on the solution since (-3, 0) is on both lines!)
Graph the two lines using the points found above.
The solution is x = -3, y = 0.
