1.x1+x2=(2a-3)/(a-1),x1*x2 = a/(a-1)
x1^2+x^2 = (x1+x2)^2-2x1x2 = 9->9(a-1)^2 = (2a-3)^2-2a = 4a^2-14a+9 = 9a^2-18a+9->5a^2-4a=0->a =0或a = 4/5
又b^2-4ac>0->4a^2-12a+9-4a^2+4a>0->-8a+9>0->a
1.x1+x2=(2a-3)/(a-1),x1*x2 = a/(a-1)
x1^2+x^2 = (x1+x2)^2-2x1x2 = 9->9(a-1)^2 = (2a-3)^2-2a = 4a^2-14a+9 = 9a^2-18a+9->5a^2-4a=0->a =0或a = 4/5
又b^2-4ac>0->4a^2-12a+9-4a^2+4a>0->-8a+9>0->a