Answer..for..all.questions
Q9.) Let 7-√5 be a rational..
7-√5= p/q (p nd q r coprimes nd q not = 0)
-√5=p/q -7
-√5= p-7q/q
√5= 7q-p/q
Since, 7, p nd q are integers therefore 7q-p/q is rational..
Therefore, √5 is also rational
But, √5 is irrational..
This contradiction arises due to our wrong assumption..
Therefore, 7-√5 is irrational..
Hope it helps u
7-√5= p/q (p nd q r coprimes nd q not = 0)
-√5=p/q -7
-√5= p-7q/q
√5= 7q-p/q
Since, 7, p nd q are integers therefore 7q-p/q is rational..
Therefore, √5 is also rational
But, √5 is irrational..
This contradiction arises due to our wrong assumption..
Therefore, 7-√5 is irrational..
Hope it helps u