Question

What is an equation for the line that passes through points (−1,−4) and (1,4)? Write the equation in slope-intercept form.

Answer 1

y = 4x

Explanation:

The slope-intercept form of an equation of a line:

`y=mx+b`

m - slope

b - y-intercept

The formula of a slope:

`m=(y_2-y_1)/(x_2-x_1)`

We have the points (1, 4) and (-1, -4).

Substitute:

`m=(-4-4)/(-1-1)=(-8)/(-2)=4`

Put it and the coordinates of the point (1, 4) to the equation of a line:

`4=4(1)+b`

`4=4+b` subtract 4 from both sides

`0=b\to b=0`

Finally we have:

`y=4x`