Please solve it with good answer and by clear way (Solve all parts of the questions)

Suppose N is the sum of squares of two integers. Prove that 2 N is also the sum of squares of two integers b) 15 pt) Show by mathematical induction that if h> 1, then it uh s (1+h" for all non-negative integers 07) 1) 14 pe] What are the coefficients of ij' and i'j' in the expansion of (41+21)