The number of integral values of x which are not in the domain of log2((x-7)/(2x-3)^2), is
Understand the Problem
The question is asking for the number of integral values of x that do not fall within the domain of a given logarithmic function. This involves understanding the conditions under which the logarithm is defined, specifically determining the restrictions on x based on the expression inside the logarithm.
Answer
The number of integral values of $x$ which are not in the domain is $8$.
Answer for screen readers
The number of integral values of $x$ which are not in the domain is $8$.
Steps to Solve
- Identify the domain restrictions for the logarithm
For the logarithmic function $\log_2\left(\frac{x-7}{(2x-3)^2}\right)$ to be defined, the argument must be greater than zero. Thus, we need to establish when:
$$ \frac{x-7}{(2x-3)^2} > 0 $$
- Analyze the numerator and denominator
The numerator $x-7$ must be greater than zero, so we solve the inequality:
$$ x - 7 > 0 \implies x > 7 $$
For the denominator $(2x-3)^2$, since a square is always non-negative and cannot equal zero, we must ensure:
$$ (2x-3)^2 \neq 0 $$
This leads us to the condition:
$$ 2x - 3 \neq 0 \implies x \neq \frac{3}{2} $$
- Combine the conditions
From the analysis, we see that:
- For $x-7 > 0$, we need $x > 7$
- The denominator condition gives $x \neq \frac{3}{2}$ (this does not impact our primary condition since $7 > \frac{3}{2}$)
Therefore, the only significant restriction is $x > 7$.
- Determine the intervals of non-valid integral values of x
Since we need integer values not in the domain, we consider integers that are less than or equal to 7. The integers to consider are:
$$ 7, 6, 5, 4, 3, 2, 1, 0, -1, \ldots $$
The relevant integral values are from negative integers up to and including 7.
- Count the integral values
The integral values of $x$ that are not in the domain are:
$$ { \ldots, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7 } $$
Counting these values gives us:
- From $-\infty$ to 7: Count all integers from negative infinity up to and including 7.
- Final count
The total count of integral values not in the domain is $8$ (from $-\infty$ to $6$), plus $7$.
The number of integral values of $x$ which are not in the domain is $8$.
More Information
This problem revolves around the properties of logarithmic functions, specifically the requirements for their arguments to be valid (i.e., greater than zero). Understanding how to analyze the numerator and denominator is essential to determine the integral values excluded from the domain.
Tips
- Misunderstanding the requirement for the logarithm, leading to incorrect inequalities.
- Ignoring the fact that the denominator cannot equal zero, which can lead to miscounting.
- Not correctly identifying all relevant intervals of $x$, particularly with inequalities.
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