I need your help for these 3 exercises. Ex.1 Considering that x+y=a+b and X2+y2=a2+b2 demonstrate that xn+yn=an+bn which n is a natural number. (n is the exponent.) Ex.2 Demonstrate that the quadratic sum of 2 odd numbers is not a full quadrate number. (It means (a+b)2 Ex.3 Considering that a x b> a+b a>0 and b>0 demonstrate that a+b>4. I hope you understand me and I am sorry for my english.