Chapter 5: Problem 56
Multiply vertically. \((4 x-5)\left(8 x^{2}+2 x-4\right)\)
Short Answer
Expert verified
The product is \(32x^3 - 32x^2 - 26x + 20\).
Step by step solution
01
Distribute the First Term of Binomial
Start by multiplying the first term of the binomial \((4x - 5)\), which is \(4x\), by each term in the trinomial \((8x^2 + 2x - 4)\). Calculate:- \(4x \cdot 8x^2 = 32x^3\)- \(4x \cdot 2x = 8x^2\)- \(4x \cdot (-4) = -16x\)This gives the result: \[32x^3 + 8x^2 - 16x\]
02
Distribute the Second Term of Binomial
Now multiply the second term of the binomial \((4x - 5)\), which is \(-5\), by each term in the trinomial \((8x^2 + 2x - 4)\).Calculate:- \(-5 \cdot 8x^2 = -40x^2\)- \(-5 \cdot 2x = -10x\)- \(-5 \cdot (-4) = 20\)This gives the result: \[-40x^2 - 10x + 20\]
03
Combine Like Terms
Now combine the results from Step 1 and Step 2. Combine like terms:- \(32x^3\) remains unchanged- \(8x^2 - 40x^2 = -32x^2\)- \(-16x - 10x = -26x\)- The constant \(20\) remains unchangedThus, the expression simplifies to:\[32x^3 - 32x^2 - 26x + 20\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distributive Property
The distributive property is a fundamental algebraic principle used in polynomial multiplication. It involves distributing, or sharing, one term across the terms of another expression. This property states that for any numbers or variables
- a,
- b,
- c,
- a(b + c) = ab + ac.
- (4x - 5) and (8x^2 + 2x - 4),
Like Terms
In algebra, like terms are terms that have identical variable parts raised to the same power. For example, in the expression
- 8x^2 - 40x^2,
- keeping terms like 32x3 as they are because no other
- '³æÂ³'
- adding
- 8x² - 40x² = -32x²
- combining
- -16x - 10x = -26x
- bringing down constant terms like 20 without any combinations.
Binomial
A binomial is a polynomial with exactly two terms. These terms can be anything, as long as there are two. Common forms include:
During multiplication, you'll find it important to treat each term in the binomial individually. In the problem (4x - 5)(8x² + 2x - 4), both 4x and -5 need to separately interact with each term in the trinomial. This captures how each portion of the binomial contributes to forming a larger polynomial. Practicing with binomials helps develop the skills needed to handle more extensive expressions.
- a + b
- x - y
- 4x - 5,
During multiplication, you'll find it important to treat each term in the binomial individually. In the problem (4x - 5)(8x² + 2x - 4), both 4x and -5 need to separately interact with each term in the trinomial. This captures how each portion of the binomial contributes to forming a larger polynomial. Practicing with binomials helps develop the skills needed to handle more extensive expressions.
Trinomial
Trinomials are polynomials that consist of three terms. They might look like:
When multiplying a trinomial like (8x² + 2x - 4) by a binomial, it’s integral to apply the distributive property to ensure each pair of terms interact. Each term of the binomial must multiply every term in the trinomial, ensuring nothing is left unaccounted.
- x² + y + z
- 8x² + 2x - 4,
When multiplying a trinomial like (8x² + 2x - 4) by a binomial, it’s integral to apply the distributive property to ensure each pair of terms interact. Each term of the binomial must multiply every term in the trinomial, ensuring nothing is left unaccounted.
- This results in more products to manage and combine, emphasizing the need for a systematic approach in algebra.
- Each pair product (e.g., the result of 4x and 8x² or -5 and -4) should be carefully calculated.
- Keep track of signs and ensure the correct combination of like terms.