Question

Stiind ca a+b=4 si a×b=2, calculati a²+b²

Answer 1

(a+b)^2 = a^2+2ab+b^2 = (a^2+b^2) +2ab
Deci a^2 +b^2 = (a+b)^2 - 2ab
Dar a+b =4 si ab=2
=> a^2 +b^2 = 4^2 -2x2 = 16-4= 12