Write an equation in slope-intercept form of the line that passes through the points (-1,-4) and (1,4)? write the equation in slope-intercept form

Question

ranga · Answer

Do you know the formula for the slope of a line connecting two points?

anonymous · Answer

no that's all it said

ranga · Answer

slope m = (y2 - y1) / (x2 - x1)

The two points are:  (-1,-4) and (1,4)
so x1 = -1, y1 = -4, x2 = 1, y2 = 4

Just plug the values into the formula and let me know what you get for m.

anonymous · Answer

I got 8/-2 is that right?

anonymous · Answer

can you help?

ranga · Answer

The slope m = ( 4 - (-4) ) / ( 1 - (-1) ) =  8 / 2 = 4

The equation of a line is: y = mx + b = 4x + b
We know the point (1, 4) lies on it;  put x = 1 and y = 4 and solve for b

4 = 4(1) + b.  So b = 0

The equation of the line is:  y = 4x