# Intersections homework help

1. Sep 27, 2004

### bob4000

how wud i do the following:

1.ax+by=c, y=2ax
2.y=mx+c, y=-mx+d
3.ax-by=1, y=x
4.some values for a,b and c for which equation does not represent a straight line, give egs

ive dun simpler versions of 1-3 but i haven't come across the above, so cud someone please tell me a simple method of working them out. thanks

2. Sep 27, 2004

### Integral

Staff Emeritus
In general, plug one equation into the other to eliminate x or y from one equation. Solve for the remaining variable, take that solution and use it to determine the other variable.

These are pretty straight forward problems, give it a bit of thought and play with what I said above.

BTW: This should be posted in the homework forum.

3. Sep 27, 2004

### bob4000

i did post the same thing in the homework section but i didnt get a reply which i needed quite badly, so i came here instead. btw. i still dont understand how to do these particular questions, i have used tht method for slightly simpler questions, but this question just puzzles me

4. Sep 27, 2004

### Chrono

How long did you wait for a reply? Don't forget that everybody here has different schedules than what you do.