Answer:
⇒ π and √ 78
Rational number:
A number that can be expressed exactly by a ratio of two integers. Integer is usually defined as one of the positive or negative numbers 1, 2, 3, etc., or zero. An example of a rational number is a repeating decimal. A repeating decimal is a decimal numeral that, after a certain point, consists of a group of one or more digits repeated as infimum, as 2.33333.... or 23.0218181818...
Irrational number:
A number that cannot be exactly expressed as a ratio of two integers. An example is a infinite decimal which is a nonterminating decimal, a decimal numeral that does not end in an infinite sequence of zeros (contrasted with terminating decimal). Example: 2.3459810212901....
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Rational numbers.
The number 9/15 is equal to 0.6 which is a terminating decimal and is therefore, rational.
18 is a whole number and integer making it rational.
9 is a integer and a whole number = rational.
169 is a integer and whole number = rational.
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Irrational numbers.
√78 ≈ 8.831760866
This decimal is a nonterminating decimal that does not terminate nor repeat making it irrational.
Now onto Pi/π which is the 16th letter of the Greek alphabet and is a known-irrational number. The ratio itself: 3.141592+. The letter is used as the symbol for the ratio of the circumference of a circle to its diameter.
So, why is PI irrational?
It relates to how pi is computed. Pi is equal to the circumference of a circle, which may be calculated by placing an n-gon within a circle. However, when the sides of the n-gon are raised, the value of pi varies every time you divide it by the diameter of the circle, therefore it is impossible to get the exact value of pi. Additionally, irrational numbers never finish or repeat their decimal expansion, therefore they cannot be tallied as 2, 3, and so on.
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Therefore, the number that are irrational is π and √78.