Question

Which equation is in slope-intercept form and represents a line with slope 3 through the point (9, –4)?

y=3x+21
y=3x-31
-3x+y=-31
-3x+y=21

Answer 1

The slope-intercept form of a line is:


`y = mx + q`

Where m is the slope and y is the y-intercept:


`y = 3x + q`

To find q (y-intercept), substitute the coordinates of the point (9, -4) in the equation of the line and solve it as an equation:

-4=3(9)+q
-4=27+q
q=-27-4=-31

The equation of the line is: y=3x-31