Answers

2016-04-07T12:45:56+05:30
√15 is rational ( contradiction method).

√15=a/b
(a and b are not common factor).

squaring on both sides, we get,

15= a^2/b^2.

15b^2=a^2 (a=15c)

b^2=15/a^2

(assume, a^2 =225c^2)

15b^2=225c^2

b^2=225c^2/15

b^2=15c^2

c^2=15/b^2

c =15/b.

15 divided both a and b which is a contradiction.

ie, √15 is irrational.




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2016-04-07T12:52:26+05:30
It is an irrational number.because if we expand it it will come as root 3 and 5.root 3 and root 5 are irrational numbers.there is no perfect square value to them.the product of two irrational numbers is a rational number.
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