Chapter 6: Rationals: Multiplication,
Division, and Applications

by
Millard Lewis and John Moore

## Day 9: Two-Step Equations

This lesson should use many of the ideas that we've discussed throughout
the last eight days. Recall that in Day 7 we discussed solving equations
and inequalities using rational numbers. The concept of solving two-steps
equations is very similar to that, but it simply involves one more step...

If we had the equation x + 5 = 6, we solved this by subtracting 5 from
both sides in order to keep our equation balanced and to get the variable
(x, in this case) by itself. This results in x = 1. We also stressed the
importance of checking our answer to make sure that we did not make a mistake.
Doing this, we see that 1 + 5 = 6, and this is true! So, we must have performed
the correct operation!

Now let's look at a two-step equation. How about 5x + 3 = 13? The first
thing that we need to do is begin to isolate the x. Start doing this by
combining the like terms, or, in this case, subtract 3 from both sides.
This leaves 5x = 10. Well, we've seen equations like this before! Multiply
both sides by the multiplicative inverse of 5, or 1/5, and we obtain x =
2. Checking our answer, we find that 5*2+3 = 13. This turns out to be true!

Now let's try some examples!

Activity: If you have access to Algebra Xpresser, try to graph your homework
problems. Most (if not all) of the graphs will be vertical lines. BUT, where
these lines cross the x-axis this the solution to the equation. Why does
this happen? What else can graphs tell us in mathematics?

Click here for your worksheet on two-step equations.

**NOTE:** Two-step equations will not appear in Day Ten's Sample Test,
but your teacher has the option to include them on your test. Ask your teacher
about this matter.