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

A. [tex]3x^4 - 6x^2 + 4[/tex]

B. [tex]4x^2 + x + 5[/tex]

C. [tex]3x^4 + 7x^3 + 7x^2 - 5x + 4[/tex]

D. [tex]3x^4 + 11x^3 + 19x^2 + 11x + 4[/tex]



Answer :

To multiply the polynomials [tex]\((x^2 + 3x + 4)\)[/tex] and [tex]\((3x^2 - 2x + 1)\)[/tex], we need to use the distributive property and multiply each term in the first polynomial by each term in the second polynomial. Here is the detailed step-by-step solution:

1. Distribute [tex]\(x^2\)[/tex] from the first polynomial to each term in the second polynomial:
[tex]\[ x^2 \cdot (3x^2 - 2x + 1) = (x^2 \cdot 3x^2) + (x^2 \cdot -2x) + (x^2 \cdot 1) = 3x^4 - 2x^3 + x^2 \][/tex]

2. Distribute [tex]\(3x\)[/tex] from the first polynomial to each term in the second polynomial:
[tex]\[ 3x \cdot (3x^2 - 2x + 1) = (3x \cdot 3x^2) + (3x \cdot -2x) + (3x \cdot 1) = 9x^3 - 6x^2 + 3x \][/tex]

3. Distribute [tex]\(4\)[/tex] from the first polynomial to each term in the second polynomial:
[tex]\[ 4 \cdot (3x^2 - 2x + 1) = (4 \cdot 3x^2) + (4 \cdot -2x) + (4 \cdot 1) = 12x^2 - 8x + 4 \][/tex]

4. Add all the terms together:
[tex]\[ 3x^4 - 2x^3 + x^2 + 9x^3 - 6x^2 + 3x + 12x^2 - 8x + 4 \][/tex]

5. Combine like terms:
[tex]\[ 3x^4 \quad \text{(only one \(x^4\) term)} \][/tex]
[tex]\[ -2x^3 + 9x^3 = 7x^3 \quad \text{(combine \(x^3\) terms)} \][/tex]
[tex]\[ x^2 - 6x^2 + 12x^2 = 7x^2 \quad \text{(combine \(x^2\) terms)} \][/tex]
[tex]\[ 3x - 8x = -5x \quad \text{(combine \(x\) terms)} \][/tex]
[tex]\[ 4 \quad \text{(only one constant term)} \][/tex]

So, putting it all together, the product of the two polynomials is:
[tex]\[ 3x^4 + 7x^3 + 7x^2 - 5x + 4 \][/tex]

Thus, the correct option is:

C. [tex]\(3x^4 + 7x^3 + 7x^2 - 5x + 4\)[/tex]