## anonymous 5 years ago find the equation of the line that contains the point (8,1) and has slope -5....thanks for the help!

1. amistre64

y = -5(x-8)+1

2. amistre64

y = -5x +41

3. anonymous

do i add -5x to both sides to solve for y?

4. anonymous

its already solved for y. Do you mean solve for x in terms of y?

5. anonymous

I guess I wanted to know if anything further needed to be done or if this was the complete answer. Sorry...I am horrible at math! :)

6. amistre64

there are many ways to express the equation of a line; this is the most common form tho.

7. anonymous

yes the usual is y=mx+c in wich this is already displayed

8. amistre64

5x+y = 41 y = -5x +41 y-1 = -5(x-8) 5x +y -41 = 0

9. anonymous

m being the gradient and c the intercept, usually the way thats most useful

10. anonymous

gotcha...thank you for the help and for the extra examples. I really appreciate it!

11. anonymous

no problem :D

12. anonymous

one more question....would the equation be the same if I have two points rather than a slope? Examples points (0,4) and (1.-3)

13. anonymous

sorry that should be (1,-3)

14. anonymous

The slope is found using diff in y / diff in x

15. anonymous

$\frac{4-(-3)}{1}$ = -7 so the equation becomes y=-7x+4

16. anonymous

so you subtracted the two y points from each other and the two x points from each other, than divide that to find the slope? so in the equation y represents the slope?

17. anonymous

sorry missed the -1 in the denominator

18. anonymous

The y represents the slope and the intercept y=Mx+C where M is the slope and C is where it crosses the y axis

19. anonymous

So the equation represent the line

20. anonymous

so in its fullness we get $y= \frac{(4-(-3))}{(0-1)}x + 4$

21. anonymous

I see it now! :D

22. anonymous

kewl :)

23. anonymous

thank u for ur patience with me!