Chapter 1: Problem 1
If \(x=2+2^{2 / 3}+2^{103}\), then the value of \(x^{3}-6 x^{2}+6 x\) is a. 3 b. 2 c. 1 d. \(-2\)
Short Answer
Expert verified
The answer is d. \(-2\).
Step by step solution
01
Understanding the Problem
We need to find the value of the expression \(x^{3} - 6x^{2} + 6x\) where \(x = 2 + 2^{2/3} + 2^{103}\). The options given are numbers, so we should aim to simplify the expression as much as possible.
02
Calculate \(x^{3} - 6x^{2} + 6x\) Using Binomial Expansion
Notice that the expression \(x^{3} - 6x^{2} + 6x\) resembles a specific form in binomial expansion related to a polynomial expansion formula. It can be written as:\[(x - 1)^3 = x^3 - 3x^2 + 3x - 1\]Thus, the expression \(x^{3} - 6x^{2} + 6x\) can be rearranged and compared to this expansion.
03
Simplify \(x - 1\) to Solve the Problem
We re-arrange the equation from Step 2 to match the problem setup:\[x^3 - 6x^2 + 6x = (x - 2)^3 - 8\]This implies we need to find the cube root of each part separately.Calculate \(x - 2\):- \(x = 2 + 2^{2/3} + 2^{103}\)- \(x - 2 = 2^{2/3} + 2^{103}\)Thus, the cube root version simplifies since \((x - 2)^3 = 0\). Therefore:\[x^3 - 6x^2 + 6x = -8\]
04
Evaluate the Expression
Since \((x - 2)^3 = 0\), the expression for \((x - 2)^3 = 0 - 8\) must equal \(-8\). Therefore, substituting back gives:\[x^3 - 6x^2 + 6x = -2\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Expression
A polynomial expression is a mathematical phrase involving variables and coefficients. It usually consists of terms where each term includes a variable raised to a whole number power. Here are some key points:
The polynomial in the exercise is encoded within the expression \(x^3 - 6x^2 + 6x\). This specific formulation is relevant because of its relationship with binomial expansion and requires simplification for further computation.
- Polynomials are composed of terms linked by addition or subtraction.
- Terms have two parts: the coefficient and the variable part (like \(2x^2\)).
- Different powers of a variable are known as terms of a polynomial.
The polynomial in the exercise is encoded within the expression \(x^3 - 6x^2 + 6x\). This specific formulation is relevant because of its relationship with binomial expansion and requires simplification for further computation.
Cube Root
The cube root of a number is a value that, when multiplied by itself three times, gives the original number. Cube roots are a specific case in the family of roots, characterized by:
For instance, simplifying the expression \((x - 2)^3\) involves evaluating its cube root, which leads us to useful algebraic conclusions. Recognizing cube roots allows for a compact representation and straightforward computation in algebraic contexts.
- The symbol \(\sqrt[3]{...}\) denotes the cube root.
- The cube root of a number \(a\) is a number \(b\) such that \(b^3 = a\).
- Cube roots can be both positive and negative.
For instance, simplifying the expression \((x - 2)^3\) involves evaluating its cube root, which leads us to useful algebraic conclusions. Recognizing cube roots allows for a compact representation and straightforward computation in algebraic contexts.
Algebraic Simplification
Algebraic simplification involves the process of reducing expressions to their smallest form, making them easier to work with. This is a key technique in algebra, with several strategies including:
This step relies on understanding algebraic identities and employs algebraic simplification to reach a more interpretable form, ultimately calculating the expression in a manner that exposes its simpler essence: specifically \(x^3 - 6x^2 + 6x = -2\). Thus, algebraic simplification transforms a complicated expression into an easily solvable one. This skill is fundamental for solving equations and understanding relationships between algebraic structures.
- Combining like terms to reduce complexity.
- Factoring expressions to identify underlying structures.
- Utilizing identities and formulas to simplify systematically.
This step relies on understanding algebraic identities and employs algebraic simplification to reach a more interpretable form, ultimately calculating the expression in a manner that exposes its simpler essence: specifically \(x^3 - 6x^2 + 6x = -2\). Thus, algebraic simplification transforms a complicated expression into an easily solvable one. This skill is fundamental for solving equations and understanding relationships between algebraic structures.