1、中考数学复习一元二次方程专练公式法解一元二次方程专项练习106题 公式法解一元二次方程12x27x+3=0(公式法)22t2t3=0,32x27x+4=042x2+2x=155y+2=3y26x2+3x4=07. 2x24x1=082x2x2=092x25x+1=010x21=4x11x2+3x3=0 123x24x2=013x2+x4=0142x26x+3=0152x23x1=0162x22x1=0173x24x1=0182x2x4=0192x2+x2=0203x2+6x4=021x2x3=0223x2+4x4=0,23(3x1)(x+2)=11x4242x25x1=025263x2+4x+
2、5=028x2x4=029302x22x1=0313x2+7x+10=18x 325x23x+2=033. 5x23x=x+1134x2+3x+1=0,354x2=2x+1365x23x=x+1373x2+7x+4=0382x23x1=0(用公式法)393x2+5x+1=0;40x24x+1=041. x24x+5=042. x2+5x+3=0432x23x6=0443x2+4x+1=0 45x24x8=0 462x2x2=0473x2+2(x1)=048x24x7=049y22y4=0 50x23x=2 512x2+x=052x2x+1=0532x29x+8=0;54. x26x+1=0;5
3、5. x2+x1=0;56. 2x26x+3=0;572x(x+4)=1 583x2+5(2x+1)=0592x24x1=0603x26x4=061x2+2x5=0 62x24x3=0634x23x1=063. x2+2x2=0; 64. y23y+1=0; 65. x2+3=2x66x24x=367. 3x22x1=0;68. ; 69. 2x27x+5=0;70. 2x27x18=071. (x+1)(x+3)=6x+4;73. x2(2m+1)x+m=074. x(x+8)=16,75. x24x=4;76. 2x22x+1=0,77. 5x2+2x1=078. 6y2+13y+6=07
4、9. 3x2+6x+9=780. 2x23x+1=0; 81. 2y(y1)+3=(y+1)282. x2=3x+1;83. (t+1)(t3)=t(33t)84x22axb2+a2=085. 3x2=25x;86. y24y=1;87. (x+1)(x1)=2x88(2x1)27=3(x+1);89x26x+11=090 5x28x+2=091x23x+1=092x2=512x93. x2+x1=0 943x24x1=0953x2+2(x1)=0,96973x24x1=098. 99. 1012x2+5x1=01022x2x1=01031043x2+5x1=01055x28x+2=0,106
5、3x2+7x+10=18x,公式法解一元二次方程106题参考答案:12x27x+3=0(公式法)a=2,b=7,c=3,b24ac=(7)2423=4924=250,方程有两个不相等的实数根,即:,x1=3,22t2t3=0,a=2,b=1,c=3,x=,32x27x+4=0a=2,b=7,c=4,b24ac=4932=17,x=,x1=,x2=42x2+2x=1由原方程,得2x2+2x1=0,该方程的二次项系数a=2,一次项系数b=2,常数项c=1;x=,x1=,x2=55y+2=3y2移项,3y25y2=0,a=3,b=5,c=2,b24ac=(5)243(2)=490,x=,x1=2,x
6、2=;6x2+3x4=0a=1,b=3,c=4,=9+414=250,x=,x1=4,x2=17. 2x24x1=0a=2,b=4,c=1,=16+42=240,x=1,x1=1+,x2=182x2x2=0a=2,b=1,c=2,b24ac=170x=即x1=,x2=92x25x+1=0a=2,b=5,c=1,b24ac=17,x=,x1=,x2=10x21=4x原方程化为一般式:x24x1=0a=1,b=4,c=1,=b24ac=(4)241(1)=20,x=2,x1=2+,x2=211x2+3x3=0 a=1,b=3,c=3;b24ac=9+12=210=,123x24x2=0a=3,b=
7、4,c=2,=b24ac=(4)243(2)=400,x=,x1=,x2=13x2+x4=0x=,x1=2,x2=142x26x+3=0a=2,b=6,c=3x=x1=,x2=;152x23x1=0a=2,b=3,c=1,=9+8=17,x=,x1=,x2=162x22x1=0a=2,b=2,c=1,b24ac=12,x=,x1=,x2=173x24x1=0一元二次方程3x24x1=0的二次项系数a=3,一次项系数b=4,常数项c=1,x=,x1=,x2=182x2x4=02x2x4=0,=,x1=,192x2+x2=0a=2,b=1,c=2(1分)b24ac=1242(2)=170(2分)(
8、4分),203x2+6x4=0a=3,b=6,c=4,b24ac=6243(4)=84,x=,即x1=,x2=21x2x3=0a=1,b=1,c=3,=(1)241(3)=130,x=,x1=,x2=223x2+4x4=0,这里a=3,b=4,c=4,b24ac=4243(4)=64,x=,x1=,x2=223(3x1)(x+2)=11x43x2+6xx2=11x4,整理得3x26x+2=0,=(6)2432=12,x=x1=,x2=242x25x1=02x25x1=0,b24ac=(5)242(1)=33,x=,即x1=,x2=25a=1,b=,c=20,b24ac=()241(20)=10
9、00,x=,x=,解得x1=+5,x2=5263x2+4x+5=0=42435=440,方程没有实数根27x24x2=0a=1,b=4,c=2,=(4)241(2)=46,x=2,x1=2+,x2=228x2x4=0a=1,b=1,c=4b24ac=1+16=170=x1=,x2=29由原方程,得t2+2t2=0,这里a=1,b=2,c=2则t=,即t1=t2=302x22x1=0a=2,b=2,c=1,b24ac=(2)242(1)=12,x=,x1=,x2=313x2+7x+10=18x 原方程可化为x2+5x+3=0,解得:325x23x+2=0b24ac=(3)24520,此方程无解3
10、3. 5x23x=x+11(公式法)5x23x=x+11,整理得:5x24x11=0,这里a=5,b=4,c=11,=16+220=236,x=,则x1=,x2=34x2+3x+1=0,这里a=1,b=3,c=1,=b24ac=94=5,x=,则x1=,x2=354x2=2x+1移项得:4x22x1=0,b24ac=(2)244(1)=20,x=,x1=,x2=365x23x=x+1方程化简为:5x24x1=0,这里a=5,b=4,c=1,=b24ac=(4)245(1)=360,x=,x1=1,x2=373x2+7x+4=03x2+7x+4=0,a=3,b=7,c=4,b24ac=4948=
11、10,x=,x1=1,x2=382x23x1=0(用公式法)a=2,b=3,c=1,=(3)242(1)=17,x=,所以x1=,x2=393x2+5x+1=0;原方程的二次项系数a=3,一次项系数b=5,常数项c=1,原方程的根是:x=,即x=;40x24x+1=0a=1,b=4,c=1,x=2;41. x24x+5=0a=1,b=4,c=5,=b24ac=1620=40,次方程无解42. x2+5x+3=0a=1,b=5,c=3,x=432x23x6=0这里a=2,b=3,c=6,=b24ac=9+48=57,x=,则x1=,x2=443x2+4x+1=0(用公式法) 二次项系数a=3,一次项系数b=4,常数项c=1,=b24ac=42431=40x=x1=1 x2=;45x24x8=0(公式法) 方程x24x8=0的二次项系数a=1、一次项系数b=4、常数项c=8,x=22,x1=2+2,x2=22;462x2x2=0a=2,b=1,c=2,b24ac=(1)242(2)=1+16=170,x=,x1=,x2=473x2+2(x1)=0整理得,3x2+2x2=0,a=3,b=
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