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經(jīng)典解法20題
（1）(3x+1)^2=7
（2）9x^2-24x+16=11
(3) (x+3)(x-6)=-8
(4) 2x^2+3x=0
(5) 6x^2+5x-50=0 (選學(xué)）
(6)x^2-4x+4=0 （選學(xué)）
(7)（x-2）^2=4（2x+3）^2
（8）y^2+2√2y-4=0
（9）（x+1）^2-3（x+1)+2=0
（10）x^2+2ax-3a^2=0（a為常數(shù)）
(11)2x^2＋7x＝4．
(12)x^2－1＝2 x
2、
（13） x^2 + 6x+5=0
(14) x ^2－4x+ 3=0
(15)7x^2 －4x－3 =0
(16)x ^2－6x+9 =0
(17)x2+8x+16=9
(18)(x2-5)2=16
(19)x(x+2)=x(3-x)+1
(20) 6x^2+x-2=0
海量111題
1)x^2-9x+8=0
(2)x^2+6x-27=0
(3)x^2-2x-80=0
(4)x^2+10x-200=0
(5)x^2-20x+96=0
(6)x^2+23x+76=0
(7)x^2-25x+154=0
3、
(8)x^2-12x-108=0
(9)x^2+4x-252=0
(10)x^2-11x-102=0
(11)x^2+15x-54=0
(12)x^2+11x+18=0
(13)x^2-9x+20=0
(14)x^2+19x+90=0
(15)x^2-25x+156=0
(16)x^2-22x+57=0
(17)x^2-5x-176=0
(18)x^2-26x+133=0
(19)x^2+10x-11=0
(20)x^2-3x-304=0
(21)x^2+13x-140=0
(22)x^2+13x-48=0
(23)x^2+5x-1
4、76=0
(24)x^2+28x+171=0
(25)x^2+14x+45=0
(26)x^2-9x-136=0
(27)x^2-15x-76=0
(28)x^2+23x+126=0
(29)x^2+9x-70=0
(30)x^2-1x-56=0
(31)x^2+7x-60=0
(32)x^2+10x-39=0
(33)x^2+19x+34=0
(34)x^2-6x-160=0
(35)x^2-6x-55=0
(36)x^2-7x-144=0
(37)x^2+20x+51=0
(38)x^2-9x+14=0
(39)x^2-29x
5、+208=0
(40)x^2+19x-20=0
(41)x^2-13x-48=0
(42)x^2+10x+24=0
(43)x^2+28x+180=0
(44)x^2-8x-209=0
(45)x^2+23x+90=0
(46)x^2+7x+6=0
(47)x^2+16x+28=0
(48)x^2+5x-50=0
(49)x^2+13x-14=0
(50)x^2-23x+102=0
(51)x^2+5x-176=0
(52)x^2-8x-20=0
(53)x^2-16x+39=0
(54)x^2+32x+240=0
(55)x^2+34x
6、+288=0
(56)x^2+22x+105=0
(57)x^2+19x-20=0
(58)x^2-7x+6=0
(59)x^2+4x-221=0
(60)x^2+6x-91=0
(61)x^2+8x+12=0
(62)x^2+7x-120=0
(63)x^2-18x+17=0
(64)x^2+7x-170=0
(65)x^2+6x+8=0
(66)x^2+13x+12=0
(67)x^2+24x+119=0
(68)x^2+11x-42=0
(69)x^20x-289=0
(70)x^2+13x+30=0
(71)x^2-24x
7、+140=0
(72)x^2+4x-60=0
(73)x^2+27x+170=0
(74)x^2+27x+152=0
(75)x^2-2x-99=0
(76)x^2+12x+11=0
(77)x^2+17x+70=0
(78)x^2+20x+19=0
(79)x^2-2x-168=0
(80)x^2-13x+30=0
(81)x^2-10x-119=0
(82)x^2+16x-17=0
(83)x^2-1x-20=0
(84)x^2-2x-288=0
(85)x^2-20x+64=0
(86)x^2+22x+105=0
(87)x^2
8、+13x+12=0
(88)x^2-4x-285=0
(89)x^2+26x+133=0
(90)x^2-17x+16=0
(91)x^2+3x-4=0
(92)x^2-14x+48=0
(93)x^2-12x-133=0
(94)x^2+5x+4=0
(95)x^2+6x-91=0
(96)x^2+3x-4=0
(97)x^2-13x+12=0
(98)x^2+7x-44=0
(99)x^2-6x-7=0
(100)x^2-9x-90=0
(101)x^2+17x+72=0
(102)x^2+13x-14=0
(103)x^2+
9、9x-36=0
(104)x^2-9x-90=0
(105)x^2+14x+13=0
(106)x^2-16x+63=0
(107)x^2-15x+44=0
(108)x^2+2x-168=0
(109)x^2-6x-216=0
(110)x^2-6x-55=0
(111)x^2+18x+32=0
答案
（1）(3x+1)^2=7
解：(3x+1)^2=7 ∴(3x+1)^2=7 ∴3x+1=±√7(注意不要丟解) ∴x= (±√7-1)/3
（2）9x^2-24x+16=11
解： 9x^2-24x+16=11 ∴(3x-4)^2
10、=11 ∴3x-4=±√11 ∴x= (±√11+4)/3 ∴原方程的解為x1=(√11+4)/3 x2=(-√11+4)/3
(3) (x+3)(x-6)=-8
解：(x+3)(x-6)=-8 化簡(jiǎn)整理得 x^2-3x-10=0 (方程左邊為二次三項(xiàng)式，右邊為零) (x-5)(x+2)=0 (方程左邊分解因式) ∴x-5=0或x+2=0 (轉(zhuǎn)化成兩個(gè)一元一次方程) ∴x1=5,x2=-2是原方程的解。
(4) 2x^2+3x=0
解：2x^2+3x=0 x(2x+3)=0 (用提公因式法將方程左邊分解因式) ∴x=0或
11、2x+3=0 (轉(zhuǎn)化成兩個(gè)一元一次方程) ∴x1=0，x2=-3/2是原方程的解。 注意：有些同學(xué)做這種題目時(shí)容易丟掉x=0這個(gè)解，應(yīng)記住一元二次方程有兩個(gè)解。
(5) 6x^2+5x-50=0 (選學(xué)）
解：6x2+5x-50=0 (2x-5)(3x+10)=0 (十字相乘分解因式時(shí)要特別注意符號(hào)不要出錯(cuò)) ∴2x-5=0或3x+10=0 ∴x1=5/2, x2=-10/3 是原方程的解。
(6)x^2-4x+4=0 （選學(xué)）
解：x^2-4x+4 =0 （∵4 可分解為2 ·2 ，∴此題可用因式分解法） (x-2)(x-2 )=0 ∴x1
12、=2 ,x2=2是原方程的解。
(7)（x-2）^2=4（2x+3）^2
解.(x-2)^2-4(2x+3)^2=0. [x-2+2(2x+3)][(x-2-2(2x+3)=0.
(5x+4)(-5x-8)=0.
x1=-4/5, x2=-8/5
（8）y^2+2√2y-4=0
解(y+√2)^2-2-4=0.
(y+ √2)^2=6.
y+√2=√6.
y=-√2±√6.
y1=-√2+√6；
y2=-√2-√6.
（9）（x+1）^2-3（x+1)+2=0
解(x+1-1)(x+1-2)=0.
x(x-
13、1)=0.
x1=0,
x2=1.
（10）x^2+2ax-3a^2=0（a為常數(shù)）
解 (x+3a)(x-a)=0.
x1=-3a,
x2=a.
(11)2x^2＋7x＝4．
解：方程可變形為2x^2＋7x－4＝0．
∵a＝2，b＝7，c＝－4，b2－4ac＝72－4×2×(－4)＝81＞0，
∴x＝ ．∴x1＝ ，x2＝－4．
(12)x^2－1＝2 x
解：方程可變形為x^2－2 x－1＝0．
∵a＝1，b＝－2 ，c＝－1，b2－4ac＝(－2 )2－4×1×(－1)＝16＞0．
∴x＝ ．∴x1＝ ＋2，x2＝ －2
（13）
14、x^2 + 6x+5=0
解：原方程可化為(x+5)(x+1)=0
x1=-5 x2=-1
(14) x ^2－4x+ 3=0
解：原方程可化為(x-3)(x-1)=0
x1=3 x2=1
(15)7x^2 －4x－3 =0
解原方程可化為 (7x+3)(x-1)=0
x1=-3/7 x2=1
(16)x ^2－6x+9 =0
解原方程可化為
(x-3)^2=0
x1=x2=3
(17)x2+8x+16=9
解：(x+4)2=9
x+4=3或x+4=-3
x1=-1,x2=-7
(18)(x2-5)2=16
解：x2-5=4或x2-
15、5=-4
x2=9或x2=1
x1=3,x2=-3,x3=1,x4=-1
(19)x(x+2)=x(3-x)+1
解x2+2x=3x-x2+1
2x2-x-1=0
(2x+1)(x-1)=0
x1=-1/2 x=1
(20) 6x^2+x-2=0
解原方程可化為(3x+2)(2x-1)=0
(x+2/3)(x-1/2)=0
x1=-2/3 x2=1/2
這是20道有過(guò)程的，還有一些沒(méi)有過(guò)程，只有答案的。
1)x^2-9x+8=0 答案：x1=8 x2=1
(2)x^2+6x-27=0 答案：x1=3 x2=-9
(3)x^2-2x-80=0
16、 答案：x1=-8 x2=10
(4)x^2+10x-200=0 答案：x1=-20 x2=10
(5)x^2-20x+96=0 答案：x1=12 x2=8
(6)x^2+23x+76=0 答案：x1=-19 x2=-4
(7)x^2-25x+154=0 答案：x1=14 x2=11
(8)x^2-12x-108=0 答案：x1=-6 x2=18
(9)x^2+4x-252=0 答案：x1=14 x2=-18
(10)x^2-11x-102=0 答案：x1=17 x2=-6
(11)x^2+15x-54=0 答案：x1=-18 x2=3
(12)x^2+11
17、x+18=0 答案：x1=-2 x2=-9
(13)x^2-9x+20=0 答案：x1=4 x2=5
(14)x^2+19x+90=0 答案：x1=-10 x2=-9
(15)x^2-25x+156=0 答案：x1=13 x2=12
(16)x^2-22x+57=0 答案：x1=3 x2=19
(17)x^2-5x-176=0 答案：x1=16 x2=-11
(18)x^2-26x+133=0 答案：x1=7 x2=19
(19)x^2+10x-11=0 答案：x1=-11 x2=1
(20)x^2-3x-304=0 答案：x1=-16 x2=19
(21)
18、x^2+13x-140=0 答案：x1=7 x2=-20
(22)x^2+13x-48=0 答案：x1=3 x2=-16
(23)x^2+5x-176=0 答案：x1=-16 x2=11
(24)x^2+28x+171=0 答案：x1=-9 x2=-19
(25)x^2+14x+45=0 答案：x1=-9 x2=-5
(26)x^2-9x-136=0 答案：x1=-8 x2=17
(27)x^2-15x-76=0 答案：x1=19 x2=-4
(28)x^2+23x+126=0 答案：x1=-9 x2=-14
(29)x^2+9x-70=0 答案：x1=-14
19、x2=5
(30)x^2-1x-56=0 答案：x1=8 x2=-7
(31)x^2+7x-60=0 答案：x1=5 x2=-12
(32)x^2+10x-39=0 答案：x1=-13 x2=3
(33)x^2+19x+34=0 答案：x1=-17 x2=-2
(34)x^2-6x-160=0 答案：x1=16 x2=-10
(35)x^2-6x-55=0 答案：x1=11 x2=-5
(36)x^2-7x-144=0 答案：x1=-9 x2=16
(37)x^2+20x+51=0 答案：x1=-3 x2=-17
(38)x^2-9x+14=0 答案：x1=
20、2 x2=7
(39)x^2-29x+208=0 答案：x1=16 x2=13
(40)x^2+19x-20=0 答案：x1=-20 x2=1
(41)x^2-13x-48=0 答案：x1=16 x2=-3
(42)x^2+10x+24=0 答案：x1=-6 x2=-4
(43)x^2+28x+180=0 答案：x1=-10 x2=-18
(44)x^2-8x-209=0 答案：x1=-11 x2=19
(45)x^2+23x+90=0 答案：x1=-18 x2=-5
(46)x^2+7x+6=0 答案：x1=-6 x2=-1
(47)x^2+16x+28=
21、0 答案：x1=-14 x2=-2
(48)x^2+5x-50=0 答案：x1=-10 x2=5
(49)x^2+13x-14=0 答案：x1=1 x2=-14
(50)x^2-23x+102=0 答案：x1=17 x2=6
(51)x^2+5x-176=0 答案：x1=-16 x2=11
(52)x^2-8x-20=0 答案：x1=-2 x2=10
(53)x^2-16x+39=0 答案：x1=3 x2=13
(54)x^2+32x+240=0 答案：x1=-20 x2=-12
(55)x^2+34x+288=0 答案：x1=-18 x2=-16
(56)
22、x^2+22x+105=0 答案：x1=-7 x2=-15
(57)x^2+19x-20=0 答案：x1=-20 x2=1
(58)x^2-7x+6=0 答案：x1=6 x2=1
(59)x^2+4x-221=0 答案：x1=13 x2=-17
(60)x^2+6x-91=0 答案：x1=-13 x2=7
(61)x^2+8x+12=0 答案：x1=-2 x2=-6
(62)x^2+7x-120=0 答案：x1=-15 x2=8
(63)x^2-18x+17=0 答案：x1=17 x2=1
(64)x^2+7x-170=0 答案：x1=-17 x2=10
(
23、65)x^2+6x+8=0 答案：x1=-4 x2=-2
(66)x^2+13x+12=0 答案：x1=-1 x2=-12
(67)x^2+24x+119=0 答案：x1=-7 x2=-17
(68)x^2+11x-42=0 答案：x1=3 x2=-14
(69)x^20x-289=0 答案：x1=17 x2=-17
(70)x^2+13x+30=0 答案：x1=-3 x2=-10
(71)x^2-24x+140=0 答案：x1=14 x2=10
(72)x^2+4x-60=0 答案：x1=-10 x2=6
(73)x^2+27x+170=0 答案：x1=-10
24、 x2=-17
(74)x^2+27x+152=0 答案：x1=-19 x2=-8
(75)x^2-2x-99=0 答案：x1=11 x2=-9
(76)x^2+12x+11=0 答案：x1=-11 x2=-1
(77)x^2+17x+70=0 答案：x1=-10 x2=-7
(78)x^2+20x+19=0 答案：x1=-19 x2=-1
(79)x^2-2x-168=0 答案：x1=-12 x2=14
(80)x^2-13x+30=0 答案：x1=3 x2=10
(81)x^2-10x-119=0 答案：x1=17 x2=-7
(82)x^2+16x-1
25、7=0 答案：x1=1 x2=-17
(83)x^2-1x-20=0 答案：x1=5 x2=-4
(84)x^2-2x-288=0 答案：x1=18 x2=-16
(85)x^2-20x+64=0 答案：x1=16 x2=4
(86)x^2+22x+105=0 答案：x1=-7 x2=-15
(87)x^2+13x+12=0 答案：x1=-1 x2=-12
(88)x^2-4x-285=0 答案：x1=19 x2=-15
(89)x^2+26x+133=0 答案：x1=-19 x2=-7
(90)x^2-17x+16=0 答案：x1=1 x2=16
(91)
26、x^2+3x-4=0 答案：x1=1 x2=-4
(92)x^2-14x+48=0 答案：x1=6 x2=8
(93)x^2-12x-133=0 答案：x1=19 x2=-7
(94)x^2+5x+4=0 答案：x1=-1 x2=-4
(95)x^2+6x-91=0 答案：x1=7 x2=-13
(96)x^2+3x-4=0 答案：x1=-4 x2=1
(97)x^2-13x+12=0 答案：x1=12 x2=1
(98)x^2+7x-44=0 答案：x1=-11 x2=4
(99)x^2-6x-7=0 答案：x1=-1 x2=7
(100)x^2-9x-9
27、0=0 答案：x1=15 x2=-6
(101)x^2+17x+72=0 答案：x1=-8 x2=-9
(102)x^2+13x-14=0 答案：x1=-14 x2=1
(103)x^2+9x-36=0 答案：x1=-12 x2=3
(104)x^2-9x-90=0 答案：x1=-6 x2=15
(105)x^2+14x+13=0 答案：x1=-1 x2=-13
(106)x^2-16x+63=0 答案：x1=7 x2=9
(107)x^2-15x+44=0 答案：x1=4 x2=11
(108)x^2+2x-168=0 答案：x1=-14 x2=12
(109)x^2-6x-216=0 答案：x1=-12 x2=18
(110)x^2-6x-55=0 答案：x1=11 x2=-5
(111)x^2+18x+32=0 答案：x1=-2 x2=-16
【精品文檔】第 16 頁(yè)
一元二次方程練習(xí)題 含答案(解法20題 題海111題)
