（1）3x²-2x-7=0
x²-(2/3)x-(7/3)=0
x²-(2/3)x=7/3
x²-(2/3)x+(1/3)²=(7/3)+(1/3)²
[x-(1/3)]²=22/9
x-(1/3)=±(1/3)√22
∴x1=(1/3)(1+√22),x2=(1/3)(1-√22)
(2) x²-6x-11=0
x²-6x=11
x²-6x+9=11+9
(x-3)²=20
x-3=±2√5
∴x1=3+2√5,x2=3-2√5.