Question

Find the slope of the line with equation 4x - 5y = 20. (Hint: Finding some points on the line first - perhaps the x- and y-intercepts - may help you find the slope.)

Answer 1

The slope formula is :

$m=\frac{y_2-y_1}{x_2-x_1}$

From the problem, we have the equation :

$4x-5y=20$

Find two points on the line (x and y intercepts)

For x intercept, let y = 0

$\begin{gathered} 4x-5(0)=20 \\ 4x=20 \\ x=\frac{20}{4}=5 \end{gathered}$

For y intercept, let x = 0

$\begin{gathered} 4(0)-5y=20 \\ -5y=20 \\ y=\frac{20}{-5}=-4 \end{gathered}$

The points are (5, 0) and (0, -4)

Using the formula above :

$\begin{gathered} m=\frac{-4-0}{0-5}=\frac{-4}{-5} \\ m=\frac{4}{5} \end{gathered}$

ANSWER :

The slope is 4/5