1. ## [Solved]Dbl checking answer with Reasoning rational or irrational.

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Question （1）
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Area of circle= A

Area=╥R²

A=╥(1/√╥)²

=╥ * 1/╥

A= ╥

Correction

A=╥(1/√╥)²

=╥ * 1/╥
=1

Therefore rational because can be express as a fraction.

Correction
Therefore it is rational because 1 can be express as 1/1 where both numerator and denominator is an integer.

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Question 2
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Find side length of Square.

Let side length of square =S
Given only diagonal length = √72 cm

(√72)²=2S²
72=2S²
72/2=S²
36=S²
√36=S
6=S

Therefore rational because can be express as a fraction.

Correction
Therefore it is rational because 6 can be express as 6/1 where both numerator and denominator is an integer.

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I have been prompted to provide reasons besides stating rational or irrational.
May i know is the above correct ? Especially Question 2 because i suspect that my answer might be wrong.
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2. ## Re: Dbl checking answer with Reasoning rational or irrational.

1) your answer for A is wrong (re-check the last step....what should $\pi(1/\pi)$ be?)

you need to be a little more precise about what a "fraction" is.

1/√2 looks like a fraction, but it isn't rational.

a number is rational if (and only if) it can be written as a fraction a/b WHERE

(and this is kind of important), b is not 0, and both a and b are INTEGERS.

so for 2), 6 is rational, because....6 = 6/1, 1 is not 0, and both 1 and 6 are integers.

3. ## Re: Dbl checking answer with Reasoning rational or irrational.

Correction altered in red.
Is that correct ?

I've been haunted by IGCSE's reasoning part because i had poor explaination and been googling around for answers because i had no idea what answer would be most appropriate . Though mostly been formulas. I had also followed chapters on Cambridge's IGCSE and it came with answers only and no solution.
So i thought of trying here and thanks alot.

4. ## Re: Dbl checking answer with Reasoning rational or irrational.

the denominator has to be non-zero, as well. although this is pretty obvious here, it's less obvious when you are just dealing with symbols.

5. ## Re: Dbl checking answer with Reasoning rational or irrational.

Thx for the help. I guess i'll stick with your reasoning part because it's the exact form that's required. After googling around i notice that most tends to add in in conjunction with this rule.
Rational numbers are all numbers of the form p/q, where p and q are integers and q ≠ 0.
This is the answer i want and really appreciated for the help.