Exam: 03.01 Exponents and Functions

Question 2 (Multiple Choice, Worth 1 point)

Solve [tex]\(4 \sqrt{2} + 5 \sqrt{4}\)[/tex] and explain whether the answer is rational or irrational.

A. The answer [tex]\(4 \sqrt{2} + 10\)[/tex] is irrational because the sum of a rational number and an irrational number is irrational.



Answer :

Let's solve the given expression, [tex]\( 4 \sqrt{2} + 5 \sqrt{4} \)[/tex], step by step to determine if the result is rational or irrational.

1. Evaluate the square roots:
- Calculate [tex]\( \sqrt{2} \)[/tex]. [tex]\(\sqrt{2} \approx 1.4142135623730951\)[/tex]. Since [tex]\(\sqrt{2}\)[/tex] is not a perfect square, it is an irrational number.
- Calculate [tex]\( \sqrt{4} \)[/tex]. [tex]\(\sqrt{4} = 2\)[/tex]. Since [tex]\(\sqrt{4}\)[/tex] is a perfect square, it is a rational number.

2. Multiply by the coefficients:
- Multiply [tex]\( 4 \)[/tex] by [tex]\( \sqrt{2} \)[/tex].
[tex]\[ 4 \sqrt{2} \approx 4 \times 1.4142135623730951 = 5.656854249492381 \][/tex]
- Multiply [tex]\( 5 \)[/tex] by [tex]\( \sqrt{4} \)[/tex].
[tex]\[ 5 \sqrt{4} = 5 \times 2 = 10 \][/tex]

3. Sum the results:
- Add the two products together.
[tex]\[ 4 \sqrt{2} + 5 \sqrt{4} \approx 5.656854249492381 + 10 = 15.65685424949238 \][/tex]

4. Determine the nature of the result:
- [tex]\( 4 \sqrt{2} \)[/tex] is an irrational number.
- [tex]\( 10 \)[/tex] is a rational number.
- Sum of an irrational number and a rational number is always an irrational number.

Therefore, the final answer [tex]\( 15.65685424949238 \)[/tex] is irrational because it includes an irrational component, specifically [tex]\( 4 \sqrt{2} \)[/tex].