## anonymous one year ago What is the equation of a line that passes through points (0, 4) and (-4, -8)? y = 2x + 4 y = 2x - 4 y = 3x + 4 y = 3x - 4

1. ganeshie8

start by finding the slope

2. Astrophysics

Well first find the slope, using the following formula: $m = \frac{ y_{2}-y _{1} }{ x _{2}-x _{1} }$ where your coordinates represent $(x_1,y_1)~~\text{and}~~(x_2,y_2)$ Once you manage to get that, plug in m and your first coordinates in the point - slope form: $y-y _{1}=m(x-x _{1})$ do some little algebra and eventually you will have slope - intercept form $y=mx+b$

3. anonymous

a

4. Astrophysics

That was fast

5. ganeshie8

|dw:1440081520066:dw|

6. Astrophysics

If you find the slope you can also eliminate two of the options right away

7. anonymous

c

8. ganeshie8

do you have 5 mnts to review the slope quick ? it keeps showing up in every problem, never stops

9. anonymous

ok

10. Astrophysics

|dw:1440081878302:dw| a quick image as well

11. ganeshie8

slope is a "number" that gives you some idea about how "steep" a line is

12. anonymous

i kind of remember

13. ganeshie8

in our present problem, we're given two points, connect them : |dw:1440081952473:dw|

14. ganeshie8

suppose you're walking from left side : |dw:1440082023122:dw|

15. ganeshie8

and want to climb that ramp, is it easy or difficult ?

16. anonymous

d

17. ganeshie8

why

18. anonymous

its steep

19. ganeshie8

ofcourse it is difficult because it is too much steep (slope is too much)

20. ganeshie8

good, "how much" steep it is ?

21. ganeshie8

see, "steep", "very steep", "mind blowingly steep" are not mathematical words we want to quantify the steepness, so we invent "slope"

22. anonymous

steep

23. ganeshie8

slope = rise / run look at the ramp, for every "1 foot" that you want to go to the right, you need to climb up a height of "3 feet" |dw:1440082367603:dw|