Question

Aratati ca numarul n=2x²+7x+9 este pozitiv, oricare ar fi numarul real x.

Answer 1

$n=2 x^{2} +7x+9= x^{2} +4x+4+ x^{2} +3x+ \frac{9}{4} + \frac{11}{4} =$
$(x+2)^{2}+ (x+ \frac{3}{2}) ^{2}+ \frac{11}{4}>0$