1. Variables and Like Terms Section 2-2-1

2. Variables  A variable holds a place for a number.  Any letter can be used.  x+6  3-7y  2t-3s+6r 2

3. Expressions  Does not contain and equal sign  A combination of variables, numbers and operations  An EQUATION is made of expressions

4. Equations  An equation contains an equal sign  It is made of expressions  2x-6 = 5x+2 has an expression on each side of the equation.

5. Term  A term is part of an expression that is added or subtracted.  In 3x 2 + 4x +3 3x 2, 4x and 3 are the terms.  Three parts –Variable –Exponent -The power to which the variable is raised –Coefficient – The number in front of the variable.

6. Terms  Identify the coefficient, exponent and variable for the following terms. – 7x 3 – -8x 2 – 2x – -3x 2 – 7x – x 5

7. Like Terms  For terms to be “like terms” everything must match except the coefficients.  Which of the following are like terms? 3x 2 2x 3 2x 2 7x 2

8. Like terms  Like terms can be added or subtracted.  3x + 5x  8y 2 s – 3y 2 s  What about m 3 -x 3 -7m 3