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Learn how to add and subtract polynomials with ease, a crucial skill for solving real-world problems. Practice examples to grasp the concept thoroughly. Discover the importance of framing addition of polynomials for practical scenarios such as determining picture size.
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Chapter 9 Section 2 Adding and Subtracting Polynomials
What You’ll Learn You’ll learn to add and subtract polynomials.
Why It’s Important Framing Addition of polynomials can be used to find the size of a picture
You can add polynomials by grouping the like terms together and then finding their sum.
Example One Find each sum. (4x – 3) + (2x + 5) Add in column form. 4x – 3 Align the like terms. (+) 2x + 5 6x + 2
Example Two Find each sum. (x2 + 2x – 5) + (3x2- x + 4) Add in column form. (x2 + 2x – 5) Align the like terms. (+) (3x2 - x + 4) 4x2+ x - 1
Example Three Find each sum. (2x2 + 5xy + 3y2) + (8x2- 7y2) Add in column form. (2x2 + 5xy + 3y2) Align the like terms. (+) (8x2 - 7y2) 10x2 + 5xy – 4y2
Your Turn Find each sum. (3x + 9) + (5x + 3) 3x + 9 + 5x + 3 8x + 12
Your Turn Find each sum. (-2x2 + x + 5) + (x2 – 3x + 2) -2x2 + x + 5 + x2 – 3x + 2 -x2 - 2x + 7
Your Turn Find each sum. a2 – 2ab + 4b2 + 7a2 - 2b2 8a2 – 2ab + 2b2
Your Turn Find each sum. (7m2 - 6) + (5m - 2) 7m2 - 6 + 5m - 2 7m2 + 5m -8
Review Recall that you can subtract an integer by adding its additive inverse or opposite. 2 – 3 = 2 + (-3) 5 – (-4) = 5 + 4 The additive inverse of 3 is -3. The additive inverse of -4 is 4.
Similarly, you can subtract a polynomial by adding its additive inverse. • To find the additive inverse of a polynomial, replace each term with its additive inverse.
-(a + 2) = -a – 2 -(x2 + 3x – 1) = -x2 - 3x + 1 -(2x2 - 5xy + y2) = -2x2 + 5xy - y2
Example 4 Find each difference. (6x + 5) – (3x + 1) Arrange like terms in column form. 6x + 5 6x + 5 (-) 3x + 1 Add the additive inverse. (+) -3x – 1 3x + 4
Example Five Find each difference. (2y2 – 3y + 5) – (y2 + 2y + 8) 2y2 – 3y + 5 (-) y2 + 2y + 8Add the additive inverse. 2y2 – 3y + 5 (+) -y2 - 2y – 8 y2 – 5y - 3
Example Six Find each difference. (3x2 + 5) – (-4x + 2x2 + 3) Record the terms so that the powers of x are in descending order. 3x2 + 5 (-) 2x2 - 4x + 3 Add the additive inverse. 3x2 + 5 (+) -2x2 + 4x - 3 x2 + 4x + 2
Your Turn Find each difference. (3x – 2) – (5x – 4) -2x + 2
Your Turn Find each difference. (10x2 + 8x – 6) – (3x2 + 2x – 9) 7x2 + 6x + 3
Your Turn Find each difference. 6m2 + 7 (–) -2m2 + 2m – 3 8m2 - 2m + 10
Your Turn Find each difference. (5x2 - 4x) – (2 – 3x) 5x2 - x - 2
Example Seven Word Problem The measure of the perimeter of triangle ABC is 7x + 2y. Find the measure of the third side of the triangle. B 3x – 5y 2x + y A C
Example Seven Word Problem Explore: You know the perimeter of the triangle and the measures of two sides. You need to find AC, the measure of the third side. B 3x – 5y 2x + y A C
Example Seven Word Problem Plan: The perimeter of a triangle is the sum of the measures of the three sides. To find AC, subtract the two given measures from the perimeter. B 3x – 5y 2x + y A C
Example Seven Word Problem BC Solve: AC = Perimeter – AB – BC AC = (7x + 2y) – (2x + y) – (3x – 5y) AB B Perimeter 3x – 5y 2x + y A C
Example Seven Word Problem Solve: AC = Perimeter – AB – BC AC = (7x + 2y) – (2x + y) – (3x – 5y) (7x + 2y) + (-2x – y) + (-3x + 5y) 7x + 2y -2x – y (+) –3x + 5y 2x + 6y Additive Inverse The measure of the third side is 2x + 6y. B 2x + y 3x – 5y A C
Video Examples • Adding and Subtracting Polynomials