Verify if the lines 2x-y+2=0 and x+y-4=0 are perpendicular.

We'll put both given lines in the point slope
form:

y = mx + n, where m is the slope and n is y
intercept.

y = 2x + 2

y = -x +
4

If 2 lines are perpendicular, the product of their slopes
is -1.

Comparing the given lines with the point slope form
of the line, we'll gather the facts that m1 = 2 and m2 =
-1.

We'll multiply m1 by m2 and we'll
get:

2*(-1) =
-2

Since the result is different from -1,
then the lines are not perpendicular.