Question

Write the standard form of the line that passes through (-1,-3) and (2,1)

Answer 1

4x - 3y = 5

Explanation:

The equation of a line in standard form is

Ax + By = C ( A is a positive integer and B, C are integers )

First obtain the equation in point- slope form

y - b = m(x - a)

where m is the slope and (a, b) a point on the line

Calculate m using the slope formula

m = (y₂ - y₁ ) / (x₂ - x₁ )

with (x₁, y₁ ) = (- 1, - 3) and (x₂, y₂ ) = (2, 1)

m =
`(1+3)/(2+1)` =
`(4)/(3)`

Using (a, b) = (2, 1), then

y - 1 =
`(4)/(3)` (x - 2) ← in point- slope form

Multiply both sides by 3

3y - 3 = 4(x - 2) ← distribute and rearrange

3y - 3 = 4x - 8 ( add 8 to both sides )

3y + 5 = 4x ( subtract 3y from both sides )

5 = 4x - 3y, so

4x - 3y = 5 ← in standard form