Question

Equation of a line that passes through the points (4, 5) and (7, -7).

Answer 1

y = - 4x + 21

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 ) = (4, 5 ) and (x₂, y₂ ) = (7, - 7 )

m =
`(-7-5)/(7-4)` =
`(-12)/(3)` = - 4 , then

y = - 4x + c ← is the partial equation

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

using (4, 5 )

5 = - 16 + c ⇒ c = 5 + 16 = 21

y = - 4x + 21 ← equation of line

Answer 2

y=-4x+21

Explanation:

1. Draw these points on a graph.

2. Point A is (4,5) and Point B is (7,-7).

3. You find the slope (gradient) by the Change in Height/ Change in Horizontal distance.

4. Now put that slope and one point into the "Point-Slope Formula"

5. Simplify Algebraically.