Adding, Subtracting, and Multiplying Polynomials

πŸ§‘Zayn Alazawi πŸ“…July 5th, 2020 πŸ“ŠGrade 11 Math

Let's explore the fundamental operations of adding, subtracting, and multiplying polynomials.

I. Adding Polynomials:

Definition: Adding polynomials involves combining like terms. Like terms are terms with the same variable(s) raised to the same exponent(s).

Procedure:

  1. Identify like terms in each polynomial.
  2. Combine the coefficients of like terms.

Example: \((3x^2βˆ’2x+5)+(2x^2+4xβˆ’1)\)

Solution: Combine like terms: \((3x^2+2x^2)+(βˆ’2x+4x)+(5βˆ’1)\)\(5x^2+2x+4\)

II. Subtracting Polynomials:

Definition: Subtracting polynomials is similar to addition. However, when subtracting, distribute the negative sign to all terms in the second polynomial.

Procedure:

  1. Distribute the negative sign to all terms in the second polynomial.
  2. Follow the steps for adding polynomials.

Example: \((3x^2βˆ’2x+5)βˆ’(2x^2+4xβˆ’1)\)

Solution: Distribute the negative sign: \(3x ^2 βˆ’2x+5βˆ’2x^2 βˆ’4x+1\)

Combine like terms:

\((3x ^2 βˆ’2x ^2 )+(βˆ’2xβˆ’4x)+(5+1)\)

\(x ^2 βˆ’6x+6\)

III. Multiplying Polynomials:

Definition: Multiplying polynomials involves applying the distributive property multiple times.

Procedure:

  1. Multiply each term in the first polynomial by each term in the second polynomial.
  2. Combine like terms.

Example: \((3xβˆ’2)(2x+1)\)

Solution: Use the distributive property: \(3x(2x)+3x(1)βˆ’2(2x)βˆ’2(1)\)

Combine like terms:

\(6x ^2 +3xβˆ’4xβˆ’2\)

\(6x ^2 βˆ’xβˆ’2\)

These operations are crucial in polynomial manipulation and finding solutions to various mathematical problems.

✍️Practice

  1. Evaluate:

    \((2xβˆ’3)(3x+1)\)

  2. Apply the distributive property:

    \(2x(3x)+2x(1)βˆ’3(3x)βˆ’3(1) \)

     

    Combine like terms:

    \(6x ^2 +2xβˆ’9xβˆ’3\)

    \(6x^2βˆ’7xβˆ’3 \)

  3. Evaluate:

    \((4x ^2 βˆ’7x+3)βˆ’(2x ^2 βˆ’4x+2)\)

  4. Distribute the negative sign:

    \(4x ^2 βˆ’7x+3βˆ’2x ^2 +4xβˆ’2\)

     

    Combine like terms:

    \((4x ^2 βˆ’2x ^2 )+(βˆ’7x+4x)+(3βˆ’2)\)

    \(2x ^2 βˆ’3x+1\)