Slope-intercept form:
y = mx + b
"m" is the slope, "b" is the y-intercept (the y value when x = 0)
You need to find "m" and "b".
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 -2/3
Perpendicular line's slope is 3/2
Isolate the y in the given equation
2x + y = -4 Subtract 2x on both sides
y = -2x - 4
The given line's slope is -2, so the perpendicular line's slope is 1/2
y = 1/2x + b
To find "b", plug in the point (2,-8) into the equation
y = 1/2x + b
-8 = 1/2(2) + b
-8 = 1 + b
-9 = b
