Question

Select the equation that contains the point (4, -8), and in which the graph of the line has a positive slope.

y – 8 = –4(x + 4)


y – 8 = 4(x + 4)


y + 8 = +4(x – 4)


y + 8 = –4(x – 4)

Answer 1

The third equation down is the one you want

Explanation:

What you need for this is the point-slope form of a line:

`y-y_(1) =m(x-x_(1) )`

where y1 is the y coordinate from our point and x1 is the x coordinate from our point. m is the slope. That m has to be positive, according to the instructions. So the first equation and the last one are out, since those are both negative.

If we fit our point into the point-slope form, it looks like this:

`y-(-8)=4(x-(4))`

which simplifies to

`y+8=4(x-4)`

and that matches the third equation down.