How do you solve 3- 3x \leq - 3?

1 Answer
Sep 12, 2017

x>=2

Explanation:

The first thing I see is the negative sign by the x. I don't mess with negative division in inequalities.

Instead, I'll add 3x to both sides.

3-3x<=-3
3-3x +(3x)<=-3 +(3x)

We are aloud to do this because we're adding the same quantity to both sides.

Simplified, we get:

3<=-3+3x

It has a nice even coefficient now.

Then, we'll get 3x alone so we can eventually divide.
We'll do this by adding 3 to both sides.

3+(3)<=-3+3x + (3)

Simplified, we get:

6<=3x

Now, let's divide safely, with no negative sign.

6 -:(3)<=3x-:(3)

Simplified, we get:

2<=x

Now, it's a little easier to read when x is on the left, and that's probably how your teacher wants the answer. We can flip the equation and keep the meaning the same.

2<=x becomes x>=2

If you don't believe me, just read the first equation forward and backwards. In both instances, 2 is less than or equal to x.

Finally, to finish this problem, we should check our work!

Take a number, any number. I usually start with 0 because, well, it's pretty easy to work with.

Plug in 0 to your original equation.

3-3x<=-3
3-3(0)<=-3
3<=-3

So, is 3 really less than (or equal to) -3? Obviously not! So before you start getting confused and accuse me of lying to you, let's plug zero into our answer.

2<=x
2<=0

Is 2 less than (or equal to) 0? Nope! Since it didn't work in both cases, that means we're probably right. There are two more instances I would try. The first is a number that correctly solves both equations, (so, greater than 2). The next is the number that x could be equal to, (2). I'll let you test those, though! Spoiler alert: they work :)