Question

What is the equation for of the line that passes through the point (2,-4) and has a slope of -2

Answer 1

y = - 2x

Explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Here m = - 2, thus

y = - 2x + c ← is the partial equation

To find c substitute (2, - 4) into the partial equation

- 4 = - 4 + c ⇒ c = - 4 + 4 = 0

y = - 2x ← equation of line

Answer 2

y = -2x

Explanation:

The equation of the line is y = -2x. Use the form y = mx + b and substitution to find your answer.

The problem already gave you the slope, and m represents the slope.

y = -2x + b

The problem also gave you one point. Substitute the x and y values of that point into the equation.

Point: (2, -4)

-4 = -4 + b

b = 0

Using basic algebra, we found that there is no b value. b equals 0. So all we have to write is y = -2x.