Which of the following is not an irrational numbera) 7√5c) (√7 – 3) - ...
Understanding Irrational Numbers
Irrational numbers are numbers that cannot be expressed as a fraction of two integers. Their decimal expansions are non-repeating and non-terminating. Let's analyze each option to identify which one is not an irrational number.
Option Analysis
- a) 7√5
- This expression involves the square root of 5, which is irrational. Multiplying an irrational number (√5) by a rational number (7) results in an irrational number. Thus, 7√5 is irrational.
- b) 2√2 + 2
- Here, 2 is a rational number and 2√2 is irrational (since √2 is irrational). The sum of a rational and an irrational number is irrational. Therefore, 2√2 + 2 is also irrational.
- c) (√7 – 3) - root 7
- This expression simplifies to -2√7 - 3. Since √7 is irrational, any linear combination of irrational numbers remains irrational. Hence, (√7 - 3) - √7 is irrational.
- d) 2√3 + 2
- Similar to option b, this expression consists of a rational number (2) and an irrational number (2√3). Their sum is irrational. So, 2√3 + 2 is also irrational.
Conclusion
Upon reviewing all options, it's clear that all provided expressions are irrational numbers. However, if we consider a mistake in interpretation, we may alternatively analyze if any option could represent a rational number.
In this context, all options are irrational, confirming that there are no rational numbers among them.
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