(1)x2-10x+25=7, 变形为:x2-10x+25-7=0, x2-10x+18=0, ∵a=1,b=-10,c=18, ∴x===5±, ∴x1=5+,x2=5-;
(2)∵a=3,b=8,c=-3, ∴x===, ∴x1=-3,x2=;
(3)∵a=1,b=-2,c=2, ∴x===, ∴x1=x2=;
(4)x2-8x=9, 变形为:x2-8x-9=0, (x-9)(x+1)=0, 则:x-9=0或x+1=0, 解得:x1=9,x2=-1;
(5)方程可变形为:2y2+y-6=0, a=2,b=1,c=-6, ∴y===, ∴y1=-,y2=1;
(6)(x-2)2=(2x+3)2. 变形为:(x-2)2-(2x+3)2=0, (x-2+2x+3)(x-2-2x-3)=0, (3x+1)(-x-5)=0, 则:3x+1=0,-x-5=0, 解得:x1=-,x2=-5. |