^2 insaeamna la puterea 2
a) 3x^2+4V3x+4+12x^2-4V3x+1-(27x^2-2)=15x^2+5-27x^2+2= -12x^2+7
b) 9x^2-6V5x+5+45x^2+6V5x+1-(28x^2-5)=54x^2+6-28x^2+5=26x^2+11
c)6x^2+2V12x+2+3-4V3x+4x^2-(18-3x^2)=10x^2+4V3x+5-4V3x-19+3x^2=13x^2-14
d)5-6V5x+9x^2+15+2V45x+9x^2-(27-4x^2)=20-6V5x+18x^2+6V5x-27+4x^2=22x^2-7