Question

Work out the equation of the straight line that passes through (5, 4) and (8, 19). Give your answer in the form y = mx + c, where m and c are integers or fractions in their simplest forms.​

Answer 1

y = 5x - 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 ) = (5, 4 ) and (x₂, y₂ ) = (8, 19 )

m =
`(19-4)/(8-5)` =
`(15)/(3)` = 5 , then

y = 5x + c ← is the partial equation

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

using (5, 4 ) , then

4 = 5(5) + c = 25 + c ( subtract 25 from both sides )

- 21 = c

y = 5x - 21 ← equation of line