Which is 2. So yes, the square root of y^2 is y.
But what about the square root say of -2 ^ 2.
If that y is negative, this is the square root of 4, which is 2.
So these aren't equal, they're the negatives of each other.
So be very careful here, it's a very common mistake.
Therefore the inequality, that we need to solve, is at the absolute value of |x -
6| <= 9. And remember when solving absolute value
inequalities, this means that negative 9 has to be less than or equal to x - 6 has
to be less than or equal to 9. So this translates into this compound
inequality. And now we can add 6 everywhere.
Which gives us, -9 + 6 is less than or = to x.
Is less than or = to 9 + 6. Or -3 is less than or = to x, is less
than or = to 15. Which we can write in integral notation
as the integral negative 3 up to 15. Or we could even graph it, the solution
set would be the integral from -3 including -3 all the way up to 15.
Including 15. So just be really careful that you use
the absolute value here. Alright.
[SOUND] Let's see another example. Let's solve this inequality for y.
Again we have the square root of something squared.
And be careful the number is the absolute value of that thing.
Which needs to be greater than 5. So when solving absolute value
inequalities, if we have the absolute value of something as larger than 5, then
that means that, that quantity is either larger than 5 or that quantity.
Is smaller than -5. And now we'll solve this compound
inequality, by working each side separately.
Solving this first inequality, we subtract 3 from both sides, which gives
us -2y Is greater than 5 - 3 or negative 2y is greater than 2.
And now we'll divide both sides by negative 2.
But remember we have to flip or reverse the direction of this inequality.
Which gives us y is less than negative 1. Alright, and what about the second
inequality? Again, we'll subtract 3 from both sides, which gives us negative 2y is
less than negative 5 - 3. Or -2y is less than -8.
Again, dividing by -2 and flipping or reversing the direction of our inequality
gives us that y is greater than 4. And because these inequalities are joined
by the word or, our solution here will be the set of all Y that make at least 1 of
these inequalities true. So graphing this gives us the following.
Let's say this is negative 1. Less than -1, we do not want to include
-1, so we put an open circle and less than, and we go to the left.
And let's say is this 4. We do not want to include 4, so we put an
open circle greater than and we go to the right, which will be our answer here.
And in an interval notation. We could write negative infinity up to
-1, open parentheses, because we don't want to include -1.
Union, again open parenthese at 4 up to infinity.
So just be very careful that you use this absolute value here when starting Thank
you, and we'll see you next time. [MUSIC]