UNDOING OPERATIONS
Please do these problems in your Composition Notebooks!!!
STEP 1 –
Choose a secret number (It’s a secret! Don’t tell!!) Now choose four more numbers (other than zero) and in any
random order add one of them, multiply by another, subtract another, and divide by the final number. Record in
words what you did and your final result on your half sheet of paper. Do not record your secret number!
For example:
I took my secret number, divided by 4, added 7, multiplied by 2, and subtracted 8. The result
was 28
STEP 2 –
Use the description on the paper given to you to complete a blank table like this one:
STEP 3 –
Now add another column listing the operations needed to undo each step.
STEP 4 –
Add a fifth column and put the final result in the bottom right cell. Then work up the table from the bottom,
undoing each operation as shown, to discover the original number. Was this the secret number? (Ask your
partner if you got it right!)
UNDOING OPERATIONS
For the following equation try to fill out the description column (what is being done to this “secret
number”?) and then use the undo column to find the secret number, x
(HINT: you’re using order of operations to go through each step in the “Description” column, and then
working the operations backwards in the “Undo” column
3 + 2(𝑥 − 4)
+ 6 = 11
5
Description
Expression
Result
Undo
1. Solve these equations using a table:
a.
𝑥−5
2
=5
Description Expression
b.
Result
Undo
𝒚+𝟏
𝟑
=𝟐
Description Expression
Result
Undo
c.
𝒙+𝟒
𝟑
= −𝟖
Description Expression
e.
7
d.
Result
Undo
𝒙+𝟔
𝟒
Description Expression
x3
 42
4
Description
Expression
= −𝟕
Result
Undo
Result
Undo