could you please help me solve these three questions thanks

5. Prove that x/S + W is an irrational number. Prove that x/i + x/g + x/E: is an irrational number. 6. Let n 2 2 be a natural number such that n divides (n 1)! + 1. Prove that n must be a prime number. 7. Let a, (3,0 be natural numbers such that ab = c2 and gcd(a,b) = 1. Show that there exists natural numbers u and U such that a = 11,2 and b = 122