Question

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

Answer 1

Answer:

-1 and -5

Step-by-step 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

$\frac{5u}{5}=\frac{-5}{1}$

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?

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