解下列方程：(1)196x^2-1=0；(2)4x^2+12x+9=81；(3)x^2-7x-1=0；(4)2x^2+3x=3；(5)x^2-2x+1=25；(6)x(2x-5)=4x-10；(7)x^2+5x+7=3x+11；(8)1-8x+16x^2=2-8x。

解：(1)196$$x^2$$-1=0

     196$$x^2$$=1$$\Longrightarrow $$$$x=\pm\frac{1}{14}$$

  (2)4$$x^2$$+12x+9=81

     4$$x^2$$+12x-72=0$$\Longrightarrow $$x²+3x-18=0$$\Longrightarrow $$$$(x-3)(x+6)=0$$$$\Longrightarrow $$$$x_1=3,x_2=-6$$

  (3)$$x^2$$-7x-1=0

    $$(x-\frac72)^2=\frac{53}{4}$$$$\Longrightarrow $$$$x=\pm\frac{\sqrt{53}}{2}+\frac72$$

  (4)2$$x^2$$+3x=3

     2$$x^2$$+3x-3=0$$\Longrightarrow $$$$2(x^2+\frac32x)-3=0$$$$\Longrightarrow $$$$2(x+\frac34)^2=\frac{33}{8}$$$$\Longrightarrow $$ $$(x+\frac34)^2=\frac{33}{16}$$$$\Longrightarrow $$$$x=\pm \frac{\sqrt{33} }{4} -\frac{3}{4}$$

  (5)$$x^2$$-2x+1=25

   $$x^2$$-2x-24=0$$\Longrightarrow $$(x-6)(x+4)=0$$\Longrightarrow $$ $$x_1=6,x_2=-4$$              

  (6)x(2x-5)=4x-10

     2$$x^2$$-9x+10=0$$\Longrightarrow $$(x-2)(2x-5)=0$$\Longrightarrow $$ x=2或x=$$\frac52$$

 (7)$$x^2$$+5x+7=3x+11

     $$x^2$$+2x-4=0$$\Longrightarrow $$(x+1)²=5$$\Longrightarrow $$$$x=\pm\sqrt{5}-1$$

 (8)1-8x+16$$x^2$$=2-8x

    $$16x^2=1$$$$\Longrightarrow $$ $$x²=\frac{1}{16}$$$$\Longrightarrow $$ $$x=\pm\frac{1}{4}$$