College

Multiply the following expressions:

[tex]\left(x^4+1\right)\left(3x^2+9x+2\right)[/tex]

A. [tex]x^4+3x^2+9x+3[/tex]
B. [tex]3x^6+9x^5+2x^4+3x^2+9x+2[/tex]
C. [tex]3x^7+9x^6+2x^5[/tex]
D. [tex]3x^8+9x^4+2x^4+3x^2+9x+2[/tex]

Answer :

To multiply the polynomials [tex]\( (x^4 + 1) \)[/tex] and [tex]\( (3x^2 + 9x + 2) \)[/tex], we should apply the distributive property, also known as the FOIL method in simpler cases. Here's a step-by-step breakdown of the process:

1. Distribute each term in the first polynomial to every term in the second polynomial.

The first polynomial is [tex]\( x^4 + 1 \)[/tex] and the second polynomial is [tex]\( 3x^2 + 9x + 2 \)[/tex].

2. Multiply [tex]\( x^4 \)[/tex] by each term in the second polynomial:
- [tex]\( x^4 \times 3x^2 = 3x^6 \)[/tex]
- [tex]\( x^4 \times 9x = 9x^5 \)[/tex]
- [tex]\( x^4 \times 2 = 2x^4 \)[/tex]

3. Multiply [tex]\( 1 \)[/tex] by each term in the second polynomial:
- [tex]\( 1 \times 3x^2 = 3x^2 \)[/tex]
- [tex]\( 1 \times 9x = 9x \)[/tex]
- [tex]\( 1 \times 2 = 2 \)[/tex]

4. Combine all the products:
Bring together all the terms obtained from the multiplication:
- [tex]\( 3x^6 + 9x^5 + 2x^4 + 3x^2 + 9x + 2 \)[/tex]

5. Simplify the expression:
Since there are no like terms to combine, the final expression remains as:
- [tex]\( 3x^6 + 9x^5 + 2x^4 + 3x^2 + 9x + 2 \)[/tex]

Therefore, the result of multiplying these two polynomials is [tex]\( 3x^6 + 9x^5 + 2x^4 + 3x^2 + 9x + 2 \)[/tex].