Answer:
When the solution is negative
Step-by-step explanation:
One example, let's say you are buying pens and each pen cost 3 dollars and you cannot spend more than 15 dollars, how many pens can you buy?
The inequality would be 3x < 15, so any negative solution is not reasonable because you cannot buy negative pens. The same goes for most real-world problems dealing with time, money, or distance.
It depends on what the question looks like. If it looks like this:
(6-3)(2/5)=
(3)(0.4)=
1.2
The way to get the equation for the radius (r) is to get r by itself. So divide each side by 4pi
500/4pi=r^2
Now take the square root of each side to get the equation of r.
sqrt(500/4pi)=r