Question

prove that√5+√7is an irrational number

Answer 1

Let 5+√7 be a rational number 
Now 5+√7=a/b 
a/b-5=√7 
a-5b/b=√7. 
Now if p is a +ve prime then √p is irrational. 
Therefore √7 is irrational. 
Hence, 5+√7 is an irrational number

Answer 2

$\sqrt{5} + \sqrt{7}$
is an irrational no. because the addition or subtraction of two irrational no.s will be irrational...
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