Step-by-step explanation:

and,

represents perpendicular lines.
Two lines are perpendicular when product of their slopes = -1
In, y =½x+4
m1 = ½
In y = -2x -3
m2 = -2
Now, m1× m2 = ½× (-2) = -1
Answer: The answer is 15
HOPE THIS HELPS AND HAVE A VERY GOOD DAY

<h3>
Step-by-step explanation:</h3>
Yes, it's true sometimes we don't use negative value of 'x'.
So, we conclude it's True.
<h3>
Hope it help you</h3>