Adding and Subtracting Polynomials

Section 9-2

Adding Polynomials

We have 2 methods to add polynomials

Method 1:

You can add polynomials by grouping the like terms horizontally together and finding their sum.

Method 2:

You can add polynomials by grouping the like terms vertically together (stacking method) and finding their sum.

Find each sum.

1. (4x - 3) + (2x + 5)

Method 1 Method 2

2. (x2 + 2x – 5) + (3x2 – x + 4)

3. (2x2 + 5xy + 3y2) + (8x2 – 7y2)

Your Turn!

1. (3x + 9) + (5x + 3)

2. (-2x2 + x + 5) + (x2 - 3x + 2)

3. (a2 - 2ab + 4b2) + (7a2 - 2b2)

4. (7m2 – 6) + (5m - 2)

Subtracting Polynomials

Recall that subtracting an integer is really adding its opposite.

4 - 3 = 4 + -3 2 – 3 = 2 + -3

To subtracting polynomials ADD THE OPPOSITE!

Find each difference

1. (6x + 5) – (3x + 1)

2.) (2y2 – 3y + 5) – (y2 + 2y +8)

3.) (3x2 + 5) – (-4x + 2x2 + 3)

Your Turn!

1. (3x – 2) – (5x – 4)

2. (10x2 + 8x - 6) – (3x2 + 2x – 9)

3. (6m2 + 7) – (-2m2 + 2m - 3)

4. (5x2 – 4x) – (2 – 3x)

Geometry Link!

The perimeter of triangle ABC is 7x + 2y. Find the measure of the third side of the triangle.

2x+ y 3x - 5y