Question

Which pair of equations represents two perpendicular lines ? Please help !!

Answer 1

Slope-intercept form:

y = mx + b   "m" is the slope, "b" is the y-intercept

For lines to be perpendicular, their slopes have to be the opposite/negative reciprocal (flipped sign and number)

For example:

slope is 2

perpendicular line's slope is -1/2

slope is -3/4

perpendicular line's slope is 4/3

#1: The slopes are the same, meaning they are parallel lines

#2: First isolate the "y" in the first equation

-4x + 5y = -5

5y = -5 + 4x

y = -1 + 4/5x   They are not perpendicular because the slopes are 4/5 and -4/5

#3: Isolate "y" in the second equation

8y = 3x - 32

y = 3/8x - 4         They are perpendicular

#4: Isolate "y" is the 1st equation

10y = -9x

y = -9/10x     They are parallel lines

The 3rd choice is your answer