Hello, PaulAdrienMauriceDirac!

I'll do part (a).

I hope you understand the reasoning.

We know that: .

Sum of roots: .

Sum of pairs: .

. . . . . . . . .

. . . . . . . . .

Product of roots: .

. . . . . . . . . . .

. . . . . . . . . . .

Therefore: .