Chapter 3: Problem 63
Perform the indicated operations and simplify as completely as possible. $$x^{2}\left(x^{3}-4 x\right)-\left(2 x^{5}-4 x^{3}\right)$$
Short Answer
Expert verified
\(-x^5\)
Step by step solution
01
- Distribute the exponent in the first expression
Multiply each term inside the first parenthesis by the term outside: \(x^2 \cdot (x^3 - 4x)\). This results in: \(x^2 \cdot x^3 - x^2 \cdot 4x = x^5 - 4x^3\).
02
- Recognize the subtraction
Subtract the second expression \((2x^5 - 4x^3)\) from the simplified first expression \((x^5 - 4x^3)\).
03
- Perform the subtraction
Combine like terms by subtracting the coefficients: \(x^5 - 4x^3 - 2x^5 + 4x^3\).
04
- Simplify the expression
Combine like terms to simplify further: \( (1x^5 - 2x^5) + (-4x^3 + 4x^3) = -x^5 + 0\).
05
- Write the final simplified expression
The simplified result is: \(-x^5\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distributing Exponents
When you see an expression like \(x^2(x^3 - 4x)\), you need to distribute \(x^2\) to each term inside the parentheses. In this case, distribute \(x^2\) to both \(x^3\) and \(4x\).
Here’s what you get:
Remember, when multiplying terms with the same base, you add their exponents. That’s why \(x^2 \times x^3\) becomes \(x^{2+3} = x^5\). Also, distribute the negative sign appropriately to get the correct result.
Here’s what you get:
- \(x^2 \times x^3 = x^{2+3} = x^5\)
- \(x^2 \times (-4x) = -4x^{2+1} = -4x^3\)
Remember, when multiplying terms with the same base, you add their exponents. That’s why \(x^2 \times x^3\) becomes \(x^{2+3} = x^5\). Also, distribute the negative sign appropriately to get the correct result.
Combining Like Terms
Like terms are terms that have the same variable raised to the same power. For example, \(x^3\) and \(-4x^3\) are like terms, but \(x^3\) and \(x^5\) are not. In the expression \(x^5 - 4x^3 - (2x^5 - 4x^3)\), we need to identify and combine like terms.
First, simplify each part within the parentheses:
First, simplify each part within the parentheses:
- The first expression is already simplified to \(x^5 - 4x^3\).
- The second expression remains \(2x^5 - 4x^3\).
- For \(x^5\): Combine \(x^5\) from the first group and \(-2x^5\) from the second group to get \((1-2)x^5 = -x^5\).
- For \(x^3\): Combine \(-4x^3\) from both groups to get \(-4x^3 + 4x^3 = 0\).
Simplifying Expressions
Simplifying an expression means reducing it to its simplest form. After distributing and combining like terms, let's simplify further.
Given: \(x^5 - 4x^3 - (2x^5 - 4x^3)\).
From the previous step, we know our terms are \(x^5 - 4x^3 - 2x^5 + 4x^3\).
Now, combine the like terms:
This step-by-step reduction helps ensure you arrive at the simplest form of a polynomial.
Given: \(x^5 - 4x^3 - (2x^5 - 4x^3)\).
From the previous step, we know our terms are \(x^5 - 4x^3 - 2x^5 + 4x^3\).
Now, combine the like terms:
- \(x^5\) and \(-2x^5\): These terms simplify to give \(-x^5\)
- \(-4x^3\) and \(4x^3\): These cancel each other out, giving \(0\).
This step-by-step reduction helps ensure you arrive at the simplest form of a polynomial.
Subtraction of Polynomials
Subtracting polynomials involve changing the sign of each term in the polynomial being subtracted and then combining like terms. Starting with \((x^5 - 4x^3) - (2x^5 - 4x^3)\), distribute the negative sign in the second polynomial:
The expression becomes \(x^5 - 4x^3 - 2x^5 + 4x^3\).
Each term in \(2x^5 - 4x^3\) is taken to the opposite sign:
Remember to change the signs when subtracting, then combine like terms to reach the simplified form.
The expression becomes \(x^5 - 4x^3 - 2x^5 + 4x^3\).
Each term in \(2x^5 - 4x^3\) is taken to the opposite sign:
- \(2x^5\) becomes \(-2x^5\).
- \(-4x^3\) becomes \(4x^3\).
- \(x^5 - 2x^5 + (-4x^3 + 4x^3)\).
- Simplify by performing the arithmetic: \(x^5 - 2x^5 = -x^5\) and \(-4x^3 + 4x^3 = 0\).
Remember to change the signs when subtracting, then combine like terms to reach the simplified form.