3a2 + 4az + -6b What is the coefficient in each term? Notice that it is obvious when we write + -6b, but when this is simplified to a single subtraction sign, it is less clear. a2 + 2b – 6b

3a2 -a2 a2 2a2 2b2 Which of these are like terms? Which are unlike? What is the coefficient and what is the order of each term? 3a3 6 3ab3

2x3 and 2x Whiteboards: Give me an example of two like terms containing the variable g. Give me an example of a variable with a coefficient of 6. 3ab2 and 2b2

3x2 + 2x2 To combine like terms we must add together the coefficients of like terms. 5ab2 - 3ab2 + ab2

6a + 3a2 + 4a Remember that if a term is being subtracted, that is the same as adding the negative term, so really the bottom one is 5 + -3, or 2. 5b2 - 2b3 - 3b2

2z - 1 - 3z + 6z – z + 3 3ab - 2b3 - + ab - 3b3

3a + 5a + 6 6 + z + 4z + 1 8z + 6 – 4z 3b – 4b + b2 2y + y – 5y 6) -x - y + 4y - x 7) 2x – 3 + 2y - 1 8) 2p – 4q + 3 - p 9) 10x2 + 3x – 4x2 10) 6 – y + 2y2

3a + 5a + 6 6) -x - y + 4y - x 6 + z + 4z + 1 7) 2x – 3 + 2y - 1 3b – 4b + b2 2y + y – 5y 6) -x - y + 4y - x 7) 2x – 3 + 2y - 1 8) 2p – 4q + 3 - p 9) 10x2 + 3x – 4x2 10) 6 – y + 2y2 8a + 6 -3y – 2x 5z + 7 2x + 2y – 4 4z + 6 p – 4q + 3 -b + b 6x2 + 3x 6 – y + 2y2 -2y