x^2+2√5x+2=0 x^2+2√5x+(√5)^2-3=0(x+√5)^2=3x+√5=±√3x1=-√5+√3,x2=-√5-√38x(2x+1)=1516x^2+8x=15x^2+1/2x=15/16x^2+1/2x+1/16=1/16+15/16(x+1/4)^2=1x+1/4=±1x=-1/4±1x1=3/4,x2=-5/4