Transcript Solving Two-Step Equations #2

Solving 2-Step Variable
Equations
What???
Relax!!
You’ve already learned 1-step!
You’ll use what you already know to
solve 2-step equations.
STEP 1
The first step – figure out the order that you
would DO to solve if you knew the value of
the variable.
STEP 2
The second step – is to complete UNDO
those steps by working in reverse order
using inverse operations!
Let’s try a problem.
We would
first DO:
-Multiply by
8 then…
8x + 5 = 61
-5 -5
So to UNDO:
-Subtract 5
then…
-Divide by 8.
- Add 5 so…
8x
= 56
Whatever we do on one side, we have to
do on the other.
Now, Step 2.
This problem
has
multiplication,
so we need to
divide now.
8x = 56
8
8
x = 7
Whatever we
do on one
side, we have
to do on the
other.
Let’s try a problem.
DO
originally…
- Multiply
by -5
- Then,
add 3
-5x + 3 = 38
-3 -3
UNDO in
reverse…
-Subtract 3
-Divide by
-5x
= 35
Whatever we do on one side, we have to do
on the other.
-5
Now, Step 2.
This problem
has
multiplication,
so we need to
divide now.
-5x = 35
-5
-5
x = -7
Whatever we
do on one
side, we have
to do on the
other.
Let’s try another problem.
a
 9  31
4
DO
originally…
- Divide by
-4
- Subtract 9
+9 +9
UNDO in
Reverse…
- Add 9
a
4
= 40
Whatever we do on one side, we
have to do on the other.
- Multiply
by -4
Now, Step 2.
This problem
has division,
so we need to
multiply now.
a = -160
Whatever we
do on one
side, we have
to do on the
other.
Let’s try another problem.
DO
originally…
UNDO in
reverse…
-Subtract 8
- Multiply
-Divide by 3
by 3
- Add 8
a - 8 = 12
Whatever we do on one side, we have to
do on the other.
Now, Step 2.
a - 8 = 12
+8 +8
a = 20
Whatever we
do on one
side, we have
to do on the
other.
Now you try some problems.
Copy these problems onto a piece of paper.
Break each problem into 2 parts to solve.
Show all your work!
7f + 5 = 40
Now you try some problems.
Copy these problems onto a piece of paper.
Break each problem into 2 parts to solve.
Show all your work!
7f + 5 = 40
t=5
t = 186
m = 100
y = -80