How do you write an equation of a line with slope of -3 and passing through (-2,4)?

2 Answers
Mar 9, 2018

y=-3x-2

Explanation:

Given -

Slope of the line -3

Point (-2, 4)

Use the formula -

mx+c=y

Where -

m slope of the line
x, y x and y coordinates, through which the line passes

in our case -

m=-3
x=-2
y=4

(-3)(-2) +C=4

6+c=4

c=4-6=-2

-3x-2=y

The equation of the required line is

y=-3x-2

Mar 9, 2018

y = -3x - 2

Explanation:

There are three ways to write the equation of a line: slope intercept form, point slope form, and standard (general) form.

Slope Intercept Form:

y = mx + b
where m is the slope of the line ((Delta y) / (Delta x)) and b is the y-intercept.
For a line with slope -3 and point (-2,4), plug -3 in for m, -2 for x, 4 for y, and solve for b.
4 = (-3)*(-2) +b
4 = 6 + b
-2 = b
The equation in slope intercept form is y = -3x - 2

Point Slope Form:

(y-y_1) = m(x-x_1)
Where m is the slope of the line ((Delta y) / (Delta x)), y_1 is the y coordinate of a point, and x_1 is the x coordinate of a point.

For a line with slope -3 and point (-2,4), plug -3 in for m, -2 for x_1, 4 for y_1.
(y - 4) = -3(x + 2)

Standard Form:

Ax + By = C

Where A, B, and C are integers. To write an equation in standard form, rewrite the equation in point slope form so that it fits the formula for standard form.
(y - 4) = -3(x + 2)
y - 4 = -3x - 6
y + 3x - 4 = - 6

y + 3x = - 2