Prove that 3 + √5 is irrational number.
Answers
Answer:
Since rational cannot be equal to irrational no.
Therefore, our supposition is wrong that 3+√5 is a rational no. Hence it is a irrational no.
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Step-by-step explanation:
Let (3 + √5) be rational.
So, (3 + √5) = a/b [ where a and b are co-prime and b ≠ 0]
Now,
(3 + √5) = a/b
=> √5= ( a/b ) - 3
=> √5= ( a - 3b ) / b
Here, if (3 + √5) = a/b is rational then, √5= ( a - 3b ) / b is also rational.
But, it contradicts the fact that √5 is irrational number.
So, our assumption was wrong.
Thus, 3 + √5 is an irrational number. ( proved )
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