Question

Determine whether the lines are parallel, perpendicular, or neither.

9x + 3y = 12
24x + 8y = 35

Answer 1

parallel

Explanation:

Let's rewrite each equation into the slope-intercept form so that we can easily identify the slope of each line.

slope-intercept form: y= mx +c, where m is the gradient and c is the y-intercept.

9x +3y= 12

3x +y= 4 (÷3 throughout)

y= -3x +4 -----(1)

24x +8y= 35

8y= -24x +35 (-24x on both sides)

`y = - 3x+ 4 (3)/(8)` -----(2)

Thus, the slopes of the lines are both -3. Since both lines have the same gradient, they are parallel to each other.

Notes:

• parallel lines have the same gradient

• the product of the gradients of two perpendicular lines is -1

• gradient and slope has the same meaning and can thus be used interchangeably