Question

prove that 9-√7 is irrational

Answer 1

Assume 9-√7 is rational
Now bring 9 to the other side
-> -√7 =-9
-> √7 =9
But we know that 9 is a rational no and √7 is an irrational no
A rational is never equal to an irrational number

Therefore 9-√7 is irrational