Download Fundamentals of Math A.14 Name Solving One

Fundamentals of Math
A.14
Name
Solving One-step Equations
Using Addition and Subtraction
Date
Period
If I asked you to fill in these blanks, what would you tell me? How would you explain to someone else
how to solve these simple equations?
1.
5  ____  9
2. ___  7  2
3.
8  ____  0
To solve simple equations in Algebra, we let a variable take the place of the piece of the equation
which we don’t know: so our problems from above become:
1.
5 x  9
2. x  7  2
3.
8 x 0
To solve these we do the opposite of what the problem says.
If we SEE an addition sign ( + ), then we need to subtract that number from both sides of the
equation.
If we SEE a subraction sign ( - ), then we need to add that number to both sides of the equation.
We want to “be fair” to both sides, so do the same thing to both sides!
Try to solve these:
4. x  3  12
5. x  4  10
6. x  9  21
7. x  3  4
8. x  5  12
9. x  7  14
It’s always a good idea to plug-in the value we get for x to see if our value makes a true statement.
A.12
Fill in the number in the missing blank which makes a true statement.
1. 7  ___  10
2. ___  (2)  12
3. ___  9  4
4. 4  ___  1
5. ___  13  23
6. ___  (6)  3
Explain what you need to do to both sides to solve for x: then solve.
For example:
x 9  5
x 99  59
x  0  14
x  14
ADD 9 to both sides
IMPORTANT: notice how the 9’s “cancel out”This is called a “zero pair”
7. x  3  4
8. x  5  12
9. x  7  14
10. x  3  6
11. x  5  25
12. x 12  2
13. x 13  14
14. x  9  7
15. x  4  19
16. x  8  9
17. x 12  11
18. x  19  5