Question

I need to complete the equation of the line through (3 -1) and (4 7). I am really stumped on this topic, please explain the process as well! Thanks in advance!

Answer 1

Assuming you want the equation in slope intercept form, you first need to use slope formula to find the slope.

$\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

Plug in the coordinates that you have, (3,-1) and (4,7), for the x and y values respectively.

$\frac{-1-7}{3-4}$

Which reduces to 8/1=8.

The slope of your equation is 8.

Slope intercept form is: y=mx+b. m is your slope and b is your y-intercept, x and y stay unchanged.

Plug the slope in:

y=8x+b.

Now, you can plug one of the sets of coordinates into the x and y of the equation to find b. I'm using (3,-1).

-1=8(3)+b

-1=24+b

Subtract 24 from both sides.

-25=b

Now plug this into the equation!

y=8x-25 is your final equation.

I hope this helps :)