1. **Stating the problem:**
Calculate the following polynomial operations given:
For the first set:
$$A(x) = 4x^3 + 3x - 4, \quad B(x) = x^2 + x + 5$$
For the second set:
$$A(x) = 3x^3 + 2x^2 - x + 6, \quad B(x) = 2x^3 - 1, \quad C(x) = -2x^2 + 3x + 1$$
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2. **First set calculations:**
- $3B = 3(x^2 + x + 5) = 3x^2 + 3x + 15$
- $2A - B = 2(4x^3 + 3x - 4) - (x^2 + x + 5) = 8x^3 + 6x - 8 - x^2 - x - 5 = 8x^3 - x^2 + 5x - 13$
- $4A - B = 4(4x^3 + 3x - 4) - (x^2 + x + 5) = 16x^3 + 12x - 16 - x^2 - x - 5 = 16x^3 - x^2 + 11x - 21$
- $A \cdot B = (4x^3 + 3x - 4)(x^2 + x + 5)$
Multiply term by term:
$$4x^3 \cdot x^2 = 4x^5$$
$$4x^3 \cdot x = 4x^4$$
$$4x^3 \cdot 5 = 20x^3$$
$$3x \cdot x^2 = 3x^3$$
$$3x \cdot x = 3x^2$$
$$3x \cdot 5 = 15x$$
$$-4 \cdot x^2 = -4x^2$$
$$-4 \cdot x = -4x$$
$$-4 \cdot 5 = -20$$
Sum all:
$$4x^5 + 4x^4 + (20x^3 + 3x^3) + (3x^2 - 4x^2) + (15x - 4x) - 20 = 4x^5 + 4x^4 + 23x^3 - x^2 + 11x - 20$$
- $2A + 2B = 2(4x^3 + 3x - 4) + 2(x^2 + x + 5) = 8x^3 + 6x - 8 + 2x^2 + 2x + 10 = 8x^3 + 2x^2 + 8x + 2$
- $4AB = 4(4x^3 + 3x - 4)(x^2 + x + 5) = 4 \times (A \cdot B)$ from above
Multiply $A \cdot B$ by 4:
$$4 \times (4x^5 + 4x^4 + 23x^3 - x^2 + 11x - 20) = 16x^5 + 16x^4 + 92x^3 - 4x^2 + 44x - 80$$
- $B^3 = (x^2 + x + 5)^3$
First find $B^2$:
$$(x^2 + x + 5)^2 = x^4 + 2x^3 + 11x^2 + 10x + 25$$
Then multiply $B^2$ by $B$:
$$(x^4 + 2x^3 + 11x^2 + 10x + 25)(x^2 + x + 5)$$
Multiply term by term and sum:
$$x^4 \cdot x^2 = x^6$$
$$x^4 \cdot x = x^5$$
$$x^4 \cdot 5 = 5x^4$$
$$2x^3 \cdot x^2 = 2x^5$$
$$2x^3 \cdot x = 2x^4$$
$$2x^3 \cdot 5 = 10x^3$$
$$11x^2 \cdot x^2 = 11x^4$$
$$11x^2 \cdot x = 11x^3$$
$$11x^2 \cdot 5 = 55x^2$$
$$10x \cdot x^2 = 10x^3$$
$$10x \cdot x = 10x^2$$
$$10x \cdot 5 = 50x$$
$$25 \cdot x^2 = 25x^2$$
$$25 \cdot x = 25x$$
$$25 \cdot 5 = 125$$
Sum all:
$$x^6 + (x^5 + 2x^5) + (5x^4 + 2x^4 + 11x^4) + (10x^3 + 11x^3 + 10x^3) + (55x^2 + 10x^2 + 25x^2) + (50x + 25x) + 125$$
$$= x^6 + 3x^5 + 18x^4 + 31x^3 + 90x^2 + 75x + 125$$
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3. **Second set calculations:**
Given:
$$A = 3x^3 + 2x^2 - x + 6, \quad B = 2x^3 - 1, \quad C = -2x^2 + 3x + 1$$
- $A + B = (3x^3 + 2x^2 - x + 6) + (2x^3 - 1) = 5x^3 + 2x^2 - x + 5$
- $4A - 2C = 4(3x^3 + 2x^2 - x + 6) - 2(-2x^2 + 3x + 1) = 12x^3 + 8x^2 - 4x + 24 + 4x^2 - 6x - 2 = 12x^3 + 12x^2 - 10x + 22$
- $2B + 3C = 2(2x^3 - 1) + 3(-2x^2 + 3x + 1) = 4x^3 - 2 - 6x^2 + 9x + 3 = 4x^3 - 6x^2 + 9x + 1$
- $A + B + C = (3x^3 + 2x^2 - x + 6) + (2x^3 - 1) + (-2x^2 + 3x + 1) = 5x^3 + 0x^2 + 2x + 6$
- $2C \cdot B = 2(-2x^2 + 3x + 1)(2x^3 - 1)$
First multiply inside:
$$2C = -4x^2 + 6x + 2$$
Multiply by $B$:
$$(-4x^2 + 6x + 2)(2x^3 - 1)$$
Multiply term by term:
$$-4x^2 \cdot 2x^3 = -8x^5$$
$$-4x^2 \cdot (-1) = 4x^2$$
$$6x \cdot 2x^3 = 12x^4$$
$$6x \cdot (-1) = -6x$$
$$2 \cdot 2x^3 = 4x^3$$
$$2 \cdot (-1) = -2$$
Sum all:
$$-8x^5 + 12x^4 + 4x^3 + 4x^2 - 6x - 2$$
- $C^2 = (-2x^2 + 3x + 1)^2$
Square the polynomial:
$$( -2x^2 )^2 = 4x^4$$
$$2 \times (-2x^2) \times 3x = -12x^3$$
$$2 \times (-2x^2) \times 1 = -4x^2$$
$$(3x)^2 = 9x^2$$
$$2 \times 3x \times 1 = 6x$$
$$1^2 = 1$$
Sum all:
$$4x^4 - 12x^3 + ( -4x^2 + 9x^2 ) + 6x + 1 = 4x^4 - 12x^3 + 5x^2 + 6x + 1$$
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**Final answers:**
**First set:**
- $3B = 3x^2 + 3x + 15$
- $2A - B = 8x^3 - x^2 + 5x - 13$
- $4A - B = 16x^3 - x^2 + 11x - 21$
- $A \cdot B = 4x^5 + 4x^4 + 23x^3 - x^2 + 11x - 20$
- $2A + 2B = 8x^3 + 2x^2 + 8x + 2$
- $4AB = 16x^5 + 16x^4 + 92x^3 - 4x^2 + 44x - 80$
- $B^3 = x^6 + 3x^5 + 18x^4 + 31x^3 + 90x^2 + 75x + 125$
**Second set:**
- $A + B = 5x^3 + 2x^2 - x + 5$
- $4A - 2C = 12x^3 + 12x^2 - 10x + 22$
- $2B + 3C = 4x^3 - 6x^2 + 9x + 1$
- $A + B + C = 5x^3 + 2x + 6$
- $2C \cdot B = -8x^5 + 12x^4 + 4x^3 + 4x^2 - 6x - 2$
- $C^2 = 4x^4 - 12x^3 + 5x^2 + 6x + 1$
Polynomial Operations 7E379B
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