Question

Solve for u.
|5u + 15| = 10

Answer 1

-1 and -5

Explanation:

You must account for negative u values (which the abs nullifies).

So
`5u+15=10` and
`5u+15=-10` is what we have to solve for.

As for usual equations, isolate the u variable.

5u + 15 = 10

5u + 15 (-15) = 10 (-15)

5u = -5

`(5u)/(5)=(-5)/(1)`

u = -1

Now you can do the same operation for the other equation and you should get u = -5.

Let's make sure we did it right by replacing u with one of our solutions (-1 or -5).

`|5(-1)+15| = 10\\10 = 10`

That's true. What about the other one?

`|5(-5)+15|=10\\10=10`