Question

What's the equation of a line that passes through points (–1, –5) and (1, 3)?

y = 4x – 1


y = –2x


y = –x + 4


y = 14x – 2

Answer 1

y = 4x - 1

Explanation:

The equation of a line in slope- intercept form is

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

Calculate m using the slope formula

m =
`(y_(2)-y_(1) )/(x_(2)-x_(1) )`

with (x₁, y₁ ) = (- 1, - 5) and (x₂, y₂ ) = (1, 3)

m =
`(3+5)/(1+1)` =
`(8)/(2)` = 4 , then

y = 4x + c ← is the partial equation

To find c substitute either of the 2 points into the partial equation

Using (1, 3 ) , then

3 = 4 + c ⇒ c = 3 - 4 = - 1

y = 4x - 1 ← equation of line

Answer 2

y=4x-1

Explanation: