函数 定义为 ,其中 ,。
- (a)
说明你如何知道 存在。
- (b)
求出 并写出其定义域。
- (c)
精确求解 。
- (d)
因此,在不使用计算器的情况下,解不等式 。
它不会直接告诉你答案,而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的
完整解法
8(a)
1. Show that the function evaluates to the same output only if the inputs are identical.
Let for some .
2. Conclude that the function is one-to-one, satisfying the condition for an inverse to exist.
Since , is a one-to-one function.
Therefore, exists.
is a one-to-one function, hence exists.
8(b)
1. Set $y = g(x)$ and make $x$ the subject.
Let .
2. State the inverse function $g^{-1}(x)$.
3. Determine the domain of $g^{-1}$ by considering the range of $g$.
The domain of is exactly the range of .
For , the expression takes all values in .
Therefore, takes all real values.
, Domain:
8(c)
1. Set up the equation to solve for $x$.
2. Convert the logarithmic equation to an exponential form to find the exact value of $x$.
8(d)
1. Establish the domain of the inequality and the root from the numerator.
From the definition of , the domain is .
To find the critical point from the numerator, we solve (as calculated in part c):
2. Simplify the inequality by identifying any strictly positive factors within the domain.
For the domain , the factor in the denominator is strictly positive, since .
Thus, we can multiply both sides of the inequality by without reversing the inequality sign, simplifying it to:
3. Identify the remaining critical value and determine their relative order without a calculator.
We identify the remaining critical value from the denominator as .
To construct a sign test without a calculator, we determine the relative order of the domain boundary and the critical values and .
Since , it logically follows that:
So the critical points in ascending order are , , and .
4. Perform a sign test on the valid intervals and deduce the final solution.
We perform a sign test on the intervals bounded by the domain and critical values:
- For : and
- For : and
- For : and
The inequality includes equality to , which occurs at the numerator's zero, . At , the denominator is zero so the expression is undefined.
Combining these observations gives the final valid intervals.
\sqrt{3} < x \le 1+\sqrt{3} \text{ or } x > 3
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