Download 9.1 Combine Like Terms - Millikan Middle School

9.1 Combine Like Terms
Common Core Standards
8. EE.7. Solve linear equations in one variable.
a. Give examples of linear equations in one variable with one solution,
infinitely many solutions, or no solutions. Show which of these
possibilities is the case by successively transforming the given
equation into simpler forms, until an equivalent equation of the form x =
a, a = a, or a = b results (where a and b are different numbers).
b. Solve linear equations with rational number coefficients, including
equations whose solutions require expanding expressions using the
distributive property and collecting like terms.
WARM-UP
Evaluate the variable expressions if x = 3.
2) 4x
1) x + x + x + x
3) 2x + 5x
4) 7x
5) x + 3x + 4x
6) 8x
Combine Like Terms
If we don't know the value of x we can't
evaluate the expression, but can we
make the expression simpler?
5x + 2x + 3x − 7x
NOTES
There are many kinds of terms:
x, 6x, -5x are x-variable terms
y, 9y, -13y are y-variable terms
0, 1, -5, 3.2 are numerical terms
Examples
How many different kinds of terms are in the
expressions?
2x − 9
y − 5x + 7
NOTES
You can combine (add and subtract) terms that are the
same type (like) .
Examples
Simplify the expressions.
5x + 3x + 7x
13y + y
12x − 11x
− y + 7y
NOTES
But you cannot combine different kinds of terms.
Examples
Simplify the expressions.
2x + 4x + 7
− x + 7y + 3x + y
6y + 8x − 3x
EXAMPLES
Find the perimeter.
4x+3
4x+3
5x
NOTES
Always keep the + or – sign with the term after it.
Examples
Simplify the expressions.
5x + 4 − 3x + 5
7x + 4 − 7x
8 + 9x − 2 − 7x
PRACTICE
Copy the "like terms."
Circle the coefficients.
7x
−3x + 5y + 1
8y
3x
8
Simplify the expressions.
6x − x + 9 + 13
−2y + 8y − 5
17x + 3 − x − 3
5x − 7y − 6x + 8y
FINAL QUESTION
Find the perimeter.
5x
2x
2x
5x