410 likes | 1.42k Views
MODELING ADDITION OF POLYNOMIALS. +. –. +. –. +. –. 1. –1. x. –x. x 2. –x 2. Algebra tiles can be used to model polynomials. These 1 -by- 1 square tiles have an area of 1 square unit. These 1 -by- x rectangular tiles have an area of x square units.
E N D
MODELING ADDITION OF POLYNOMIALS + – + – + – 1 –1 x –x x2 –x2 Algebra tiles can be used to model polynomials. These 1-by-1 square tiles have an area of 1 square unit. These 1-by-x rectangular tiles have an area of x square units. These x-by-x rectangular tiles have an area of x2 square units.
MODELING ADDITION OF POLYNOMIALS 1 You can use algebra tiles to add the polynomials x2 + 4x + 2 and 2x2 – 3x – 1. Form the polynomials x2 + 4x + 2 and 2x2 – 3x – 1 with algebra tiles. x2 + 4x + 2 + + + + + + + 2x2 – 3x – 1 + + – – – –
MODELING ADDITION OF POLYNOMIALS 2 + + + – – – + + + + + + + – + You can use algebra tiles to add the polynomials x2 + 4x + 2 and 2x2 – 3x – 1. To add the polynomials, combine like terms. Group the x2-tiles, the x-tiles, and the 1-tiles. 2x2 – 3x – 1 x2 + 4x+ 2 + + + + + + + + – = + – – –
MODELING ADDITION OF POLYNOMIALS 3 2 + + + – – – + + + + + + + – + You can use algebra tiles to add the polynomials x2 + 4x + 2 and 2x2 – 3x – 1. To add the polynomials, combine like terms. Group the x2-tiles, the x-tiles, and the 1-tiles. 2x2 – 3x – 1 x2 + 4x+ 2 Find and remove the zero pairs. The sum is 3x2 + x + 1. + + + + + + + + – = + – – –
Adding and Subtracting Polynomials An expression which is the sum of terms of the form axk where k is a nonnegative integer is a polynomial. Polynomials are usually written in standard form. Standard form means that the terms of the polynomial are placed in descending order, from largest degree to smallest degree. Polynomial in standard form: 2x3 + 5x2– 4x + 7 Leading coefficient Degree Constant term The degree of each term of a polynomial is the exponent of the variable. The degree of a polynomial is the largest degree of its terms. When a polynomial is written in standard form, the coefficient of the first term is the leading coefficient.
Classifying Polynomials A polynomial with only one term is called a monomial. A polynomial with two terms is called a binomial. A polynomial with three terms is called a trinomial. Identify the following polynomials: Classified by degree Classified by number of terms Polynomial Degree constant monomial 6 0 linear monomial –2x 1 linear binomial 1 3x + 1 quadratic trinomial –x2 + 2x – 5 2 cubic binomial 3 4x3 – 8x quartic polynomial 4 2x4 – 7x3 – 5x + 1
Adding Polynomials + Find the sum. Write the answer in standard format. (5x3 – x + 2x2 + 7) + (3x2 + 7 – 4x) + (4x2 – 8 – x3) SOLUTION Vertical format: Write each expression in standard form. Align like terms. 5x3 + 2x2 – x + 7 3x2 – 4x + 7 – x3+ 4x2 – 8 4x3 + 9x2 – 5x + 6
Adding Polynomials Find the sum. Write the answer in standard format. (2x2 + x – 5) + (x + x2 + 6) SOLUTION Horizontal format: Add like terms. (2x2 + x – 5) + (x + x2 + 6) = (2x2 +x2) + (x + x) + (–5 + 6) = 3x2 + 2x+ 1
Subtracting Polynomials + – Find the difference. (–2x3 + 5x2 – x+ 8) – (–2x2 + 3x – 4) SOLUTION Use a vertical format. To subtract, you add the opposite. This means you multiply each term in the subtracted polynomial by –1 and add. –2x3 + 5x2 – x + 8 No change –2x3 + 5x2 – x + 8 –2x3 + 3x – 4 2x3– 3x+ 4 Add the opposite
Subtracting Polynomials + Find the difference. (–2x3 + 5x2 – x+ 8) – (–2x2 + 3x – 4) SOLUTION Use a vertical format. To subtract, you add the opposite. This means you multiply each term in the subtracted polynomial by –1 and add. –2x3 + 5x2 – x + 8 –2x3 + 5x2 – x + 8 – –2x3 + 3x – 4 2x3– 3x+ 4 5x2 – 4x + 12
Subtracting Polynomials Find the difference. (3x2 – 5x + 3) – (2x2 – x – 4) SOLUTION Use a horizontal format. (3x2 – 5x + 3) – (2x2 – x – 4) = (3x2 – 5x + 3) + (–1)(2x2 – x – 4) = (3x2 – 5x + 3) – 2x2 + x + 4 = (3x2– 2x2) + (– 5x +x) + (3+ 4) = x2 – 4x+ 7
Using Polynomials in Real Life You are enlarging a 5-inch by 7-inch photo by a scale factor of xand mounting it on a mat. You want the mat to be twice as wide as the enlarged photo and 2 inches less than twice as high as the enlarged photo. Write a model for the area of the mat around the photograph as a function of the scale factor. Use a verbal model. SOLUTION Area of photo Area of mat = Total Area – Verbal Model 7x 14x – 2 Area of mat =A (square inches) Labels 5x Total Area= (10x)(14x – 2) (square inches) 10x Area of photo= (5x)(7x) (square inches) …
Using Polynomials in Real Life A model for the area of the mat around the photograph as a function of the scale factor x is A = 105x2 – 20x. You are enlarging a 5-inch by 7-inch photo by a scale factor of xand mounting it on a mat. You want the mat to be twice as wide as the enlarged photo and 2 inches less than twice as high as the enlarged photo. Write a model for the area of the mat around the photograph as a function of the scale factor. SOLUTION … 7x A= (10x)(14x – 2) –(5x)(7x) 14x – 2 Algebraic Model = 140x2 – 20x – 35x2 5x = 105x2 – 20x 10x