## lyzzy7 2 years ago What is an equation in slope-intercept form for the line that passes through the points (1, –3) and (3, 1)? y = 3x + 1 y = x – 3 y = 2x + 5 y = 2x – 5

1. campbell_st

can you find the slope of the line...?

2. __assassin__
3. lyzzy7

yes its -2

4. __assassin__

well then just plot one of your points and keep using your slope.. down two, right one, point. down two right one point. or vice versa up two, left one, point

5. __assassin__

then use slope int. form y=mx+b where m=slope and b=y-int.

6. campbell_st

ok, so the slope intercept form of a line is \[y = mx + b\] and using your slope you have y = -2x + b so to find b pick a point (3, 1) and substitute x = 3 and y = 1 to find b. then you'll have the equation of the line.

7. lyzzy7

so b=7?

8. campbell_st

but looking at your choices... your slope calculation is incorrect... (1 - -3)/(3 - 1)

9. lyzzy7

ohh...

10. campbell_st

lets get the slope right 1st

11. lyzzy7

I still got -2..

12. lyzzy7

1- (-3) = -4. 3-1= 2. so thats -4/2, simplified to -2/1= -2

13. campbell_st

1 - -3 = 4 2 negatives make a positive so the slope is 4/2 or 2 so you have y = 2x + b substitute x = 3, y = 1 to find b and the equation of your line

14. lyzzy7

so b= -5?

15. campbell_st

thats it so your line is y = 2x - 5

16. lyzzy7

omg thank you:D <3333

17. campbell_st