Question

which of the following is not an irrational number 2-√2 2x√3 5+√5 √5x√5​

Answer 1

Answer:

 21

Let us assume 21 is rational.

So we can write this number as

21=ba ---- (1)

Here, a and b are two co-prime numbers and b is not equal to zero.

Simplify the equation (1) multiply by 2 both sides, we get

1=ba2

Now, divide by b, we get

b=a2 or ab=2

Here, a and b are integers so, ab is a rational number, 

so 2 should be a rational number.

But 2 is a irrational number, so it is contradictory.

Therefore, 21 is irrational number.

(ii) 75

Let us assume 75 is rational.

So, we can write this number as

75=b

Step-by-step explanation:

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Answer 2

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