Given the lines:

2x-y +2 = 0

x+y -4 = 0

We need to verify if the lines are perpendicular.

We will use the slope to verify.

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

First we will rewrite the lines into the slope form y=mx+b

==> 2x-y +2 = 0 ==> y= 2x+2 ==> the slope m1 = 2

==> x+y -4 = 0 ==> y= -x + 4 ==> the slope m2 = -1

==> m1*m2 = -2.

**Then the lines are not perpendicular.**

For the given lines , 2x-y+2=0 and x+y-4=0, we first find their slope.

2x - y + 2 = 0

=> -y = -2x - 2

=> y = 2x + 2

This is in the form y = mx + c , where m is the slope of the line.

So the slope is m1 = 2

For x + y - 4 = 0

=> y = -x + 4

Here the slope is m2 = -1.

Now the slope of two perpendicular lines when multiplied gives the result -1.

As m1*m2 = 2 * -1 = -2 and not -1, we cannot say that the lines 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.**

Two lines y = m1*x+c and y = m2*x+d are perpendicular if m1*m2 = -1.

We convert the given two lines in the form y = mx+c

The given 2x-y+2 = 0 could be written as y = 2x+2 ...(1). So slope m1 = 2.

x+y-4 = 0 could be written as: y = -x+4....(2). The slope m2 = -1.

We can see that the product of the slopes m1*m2 = 2*-1 = -2. Since the product of slopes m1*m2 is not equal to zero, we conclude that the given lines are not perpendicular.