x^2+3x=2(x+3/2)^2=2+9/4=17/4x+1.5=(√17)/2或x+1.5=-(√17)/2x=(√17 -3)/2或x=-(√17+3)/2
x=±√17 /2-1.5
x^2+3x=2x^2+3x-2=0x^2+3x+9/4-9/4-2=0(x+3/2)^2-9/4-2=0(x+3/2)^2=17/4x+3/2=±√17/2x1=√17/2-3/2=(√17-3)/2x2= -√17/2-3/2=( -√17-3)/2