- (i)
在不使用计算器的情况下,解不等式 。
- (ii)
由此,解不等式 。
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完整解法
5(i)
1. Rearrange the inequality to have zero on one side and combine into a single algebraic fraction.
2. Analyse the sign of the numerator.
For the numerator :
Discriminant .
Since and the coefficient of is positive (), for all real values of .
(Alternatively, by completing the square: for all .)
3. Deduce the condition for the denominator and solve the resulting quadratic inequality.
Since the numerator is strictly positive, the denominator must also be positive for the entire fraction to be greater than zero:
Factorising the quadratic expression:
Considering the roots and , the parabola opens upwards. Thus, the expression is positive outside the roots:
5(ii)
1. Solve the inequality in part (i) to establish the necessary base result.
2. Relate the target inequality to part (i) by applying a modulus substitution.
Notice that , so the inequality can be rewritten as:
This is identical to the inequality in (i) with replaced by . Using the established result:
3. Solve the resulting modulus inequalities, rejecting any invalid cases.
Since for all real , the inequality has no real solutions.
We only solve :
or
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