Question

(2x+1)la patrat-(x-1)la atrat+(x-2)(x+2)-3xpatrat+14.Aratatu ca E(X) mai mare decat 0

Answer 1

Răspuns:

E(x)=(2x+1)² -(x-1)²+(x-2)(x+2)-3x²+14

E(x)=4x²+4x+1-(x²-2x+1)+(x²-4)-3x²+14

E(x)=x²+4x+15-x²+2x-1+x²-4

E(x)=x²+6x+14

x²>0

x²>6x

14>0

=> E(x)>0