八年级下册数学计算题及答案100道
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①5√8-2√32+√50 =5*3√2-2*4√2+5√2 =√2(15-8+5) =12√2 ②√6-√3/2-√2/3 =√6-√6/2-√6/3 =√6/6 ③(√45+√27)-(√4/3+√125) =(3√5+3√3)-(2√3/3+5√5) =-2√5+7√5/3 ④(√4a-√50b)-2(√b/2+√9a) =(2√a-5√2b)-2(√2b/2+3√a) =-4√a-6√2b ⑤√4x*(√3x/2-√x/6) =2√x(√6x/2-√6x/6) =2√x*(√6x/3) =2/3*|x|*√6 ⑥(x√y-y√x)÷√xy =x√y÷√xy-y√x÷√xy =√x-√y ⑦(3√7+2√3)(2√3-3√7) =(2√3)^2-(3√7)^2 =12-63 =-51 ⑧(√32-3√3)(4√2+√27) =(4√2-3√3)(4√2+3√3) =(4√2)^2-(3√3)^2 =32-27 =5 ⑨(3√6-√4)? =(3√6)^2-2*3√6*√4+(√4)^2 =54-12√6+4 =58-12√6 ⑩(1+√2-√3)(1-√2+√3) =[1+(√2-√3)][1-(√2-√3)] =1-(√2-√3)^2 =1-(2+3+2√6) =-4-2√6 (1)5√12×√18 =5*2√3*3√2 =30√6; (2)-6√45×(-4√48) =6*3√5*4*4√3 =288√15; (3)√(12a)×√(3a) /4 =√(36a^2)/4 =6a/4 =3a/2. 5. x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2 =[x(y+z)-y(x-z)]^2 =(xz+yz)^2 =z^2(x+y)^2 6. 3(a+2)^2+28(a+2)-20 =[3(a+2)-2][(a+2)+10] =(3a+4)(a+12) 7. (a+b)^2-(b-c)^2+a^2-c^2 =(a+b)^2-c^2+a^2-(b-c)^2 =(a+b+c)(a+b-c)+(a+b-c)(a-b+c) =(a+b-c)(a+b+c+a-b+c) =2(a+b-c)(a+c) 8. x(x+1)(x^2+x-1)-2 =(x^2+x)(x^2+x-1)-2 =(x^2+x)^2-(x^2+x)-2 =(x^2+x-2)(x^2+x+1) =(x+2)(x-1)(x^2+x+1) 9. 9x^2(x-1)^2-3(x^2-x)-56 =9x^2(x-1)^2-3x(x-1)-56 =[3x(x-1)-8][3x(x-1)+7] =(3x^2-3x-8)(3x^2-3x+7) 有理数练习 练习一(B级) (一)计算题: (1)23+(-73) (2)(-84)+(-49) (3)7+(-2.04) (4)4.23+(-7.57) (5)(-7/3)+(-7/6) (6)9/4+(-3/2) (7)3.75+(2.25)+5/4 (8)-3.75+(+5/4)+(-1.5) 5. x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2 =[x(y+z)-y(x-z)]^2 =(xz+yz)^2 =z^2(x+y)^2 6. 3(a+2)^2+28(a+2)-20 =[3(a+2)-2][(a+2)+10] =(3a+4)(a+12) 7. (a+b)^2-(b-c)^2+a^2-c^2 =(a+b)^2-c^2+a^2-(b-c)^2 =(a+b+c)(a+b-c)+(a+b-c)(a-b+c) =(a+b-c)(a+b+c+a-b+c) =2(a+b-c)(a+c) 8. x(x+1)(x^2+x-1)-2 =(x^2+x)(x^2+x-1)-2 =(x^2+x)^2-(x^2+x)-2 =(x^2+x-2)(x^2+x+1) =(x+2)(x-1)(x^2+x+1) 9. 9x^2(x-1)^2-3(x^2-x)-56 =9x^2(x-1)^2-3x(x-1)-56 =[3x(x-1)-8][3x(x-1)+7] =(3x^2-3x-8)(3x^2-3x+7) 1.125*3+125*5+25*3+25 2.9999*3+101*11*(101-92) 3.(23/4-3/4)*(3*6+2) 4. 3/7 × 49/9 - 4/3 5. 8/9 × 15/36 + 1/27 6. 12× 5/6 – 2/9 ×3 7. 8× 5/4 + 1/4 8. 6÷ 3/8 – 3/8 ÷6 9. 4/7 × 5/9 + 3/7 × 5/9 10. 5/2 -( 3/2 + 4/5 ) 11. 7/8 + ( 1/8 + 1/9 ) 12. 9 × 5/6 + 5/6 13. 3/4 × 8/9 - 1/3 14. 7 × 5/49 + 3/14 15. 6 ×( 1/2 + 2/3 ) 16. 8 × 4/5 + 8 × 11/5 17. 31 × 5/6 – 5/6 18. 9/7 - ( 2/7 – 10/21 ) 19. 5/9 × 18 – 14 × 2/7 20. 4/5 × 25/16 + 2/3 × 3/4 21. 14 × 8/7 – 5/6 × 12/15 22. 17/32 – 3/4 × 9/24 23. 3 × 2/9 + 1/3 24. 5/7 × 3/25 + 3/7 25. 3/14 ×× 2/3 + 1/6 26. 1/5 × 2/3 + 5/6 27. 9/22 + 1/11 ÷ 1/2 28. 5/3 × 11/5 + 4/3 29. 45 × 2/3 + 1/3 × 15 30. 7/19 + 12/19 × 5/6 31. 1/4 + 3/4 ÷ 2/3 32. 8/7 × 21/16 + 1/2 33. 101 × 1/5 – 1/5 × 21 34.50+160÷40 35.120-144÷18+35 36.347+45×2-4160÷52 37(58+37)÷(64-9×5) 38.95÷(64-45) 39.178-145÷5×6+42 40.812-700÷(9+31×11) 41.85+14×(14+208÷26) 43.120-36×4÷18+35 44.(58+37)÷(64-9×5) 45.(6.8-6.8×0.55)÷8.5 46.0.12× 4.8÷0.12×4.8 47.(3.2×1.5+2.5)÷1.6 48.6-1.6÷4= 5.38+7.85-5.37= 49.7.2÷0.8-1.2×5= 6-1.19×3-0.43= 50.6.5×(4.8-1.2×4)= 51.5.8×(3.87-0.13)+4.2×3.74 52.32.52-(6+9.728÷3.2)×2.5 53.[(7.1-5.6)×0.9-1.15] ÷2.5 54.5.4÷[2.6×(3.7-2.9)+0.62] 55.12×6÷(12-7.2)-6 56.12×6÷7.2-6 57.0.68×1.9+0.32×1.9 58.58+370)÷(64-45) 59.420+580-64×21÷28 60.136+6×(65-345÷23) 15-10.75×0.4-5.7 62.18.1+(3-0.299÷0.23)×1 63.(6.8-6.8×0.55)÷8.5 64.0.12× 4.8÷0.12×4.8 65.(3.2×1.5+2.5)÷1.6 66.3.2×6+(1.5+2.5)÷1.6 67.0.68×1.9+0.32×1.9 68.10.15-10.75×0.4-5.7 69.5.8×(3.87-0.13)+4.2×3.74 70.32.52-(6+9.728÷3.2)×2.5 71.[(7.1-5.6)×0.9-1.15] ÷2.5 72.5.4÷[2.6×(3.7-2.9)+0.62] 73.12×6÷(12-7.2)-6 74.12×6÷7.2-6 75.33.02-(148.4-90.85)÷2.5 1) 76.(25%-695%-12%)*36 77./4*3/5+3/4*2/5 78.1-1/4+8/9/7/9 79.+1/6/3/24+2/21 80./15*3/5 81.3/4/9/10-1/6 82./3+1/2)/5/6-1/3]/1/7 83./5+3/5/2+3/4 84.(2-2/3/1/2)]*2/5 85.+5268.32-2569 86.3+456-52*8 87.5%+6325 88./2+1/3+1/4 2) 89+456-78 3) 5%+. 3/7 × 49/9 - 4/3 4) 9 × 15/36 + 1/27 5) 2× 5/6 – 2/9 ×3 6) 3× 5/4 + 1/4 7) 94÷ 3/8 – 3/8 ÷6 8) 95/7 × 5/9 + 3/7 × 5/9 9) 6/2 -( 3/2 + 4/5 ) 10) 8 + ( 1/8 + 1/9 ) 11) 8 × 5/6 + 5/6 12) 1/4 × 8/9 - 1/3 13) 10 × 5/49 + 3/14 14) 1.5 ×( 1/2 + 2/3 ) 15) 2/9 × 4/5 + 8 × 11/5 16) 3.1 × 5/6 – 5/6 17) 4/7 - ( 2/7 – 10/21 ) 18) 19 × 18 – 14 × 2/7 19) 5 × 25/16 + 2/3 × 3/4 20) 4 × 8/7 – 5/6 × 12/15 21) 7/32 – 3/4 × 9/24 22) 1、 2/3÷1/2-1/4×2/5 2、 2-6/13÷9/26-2/3 3、 2/9+1/2÷4/5+3/8 4、 10÷5/9+1/6×4 5、 1/2×2/5+9/10÷9/20 6、 5/9×3/10+2/7÷2/5 7、 1/2+1/4×4/5-1/8 8、 3/4×5/7×4/3-1/2 9、 23-8/9×1/27÷1/27 10、 8×5/6+2/5÷4 11、 1/2+3/4×5/12×4/5 12、 8/9×3/4-3/8÷3/4 13、 5/8÷5/4+3/23÷9/11 23) 1.2×2.5+0.8×2.5 24) 8.9×1.25-0.9×1.25 25) 12.5×7.4×0.8 26) 9.9×6.4-(2.5+0.24)(27) 6.5×9.5+6.5×0.5 0.35×1.6+0.35×3.4 0.25×8.6×4 6.72-3.28-1.72 0.45+6.37+4.55 5.4+6.9×3-(25-2.5)2×41846-620-380 4.8×46+4.8×54 0.8+0.8×2.5 1.25×3.6×8×2.5-12.5×2.4 28×12.5-12.5×20 23.65-(3.07+3.65) (4+0.4×0.25)8×7×1.25 1.65×99+1.65 27.85-(7.85+3.4) 48×1.25+50×1.25×0.2×8 7.8×9.9+0.78 (1010+309+4+681+6)×12 3×9146×782×6×854 5.15×7/8+6.1-0.60625 1. 3/7 × 49/9 - 4/3 2. 8/9 × 15/36 + 1/27 3. 12× 5/6 – 2/9 ×3 4. 8× 5/4 + 1/4 5. 6÷ 3/8 – 3/8 ÷6 6. 4/7 × 5/9 + 3/7 × 5/9 7. 5/2 -( 3/2 + 4/5 ) 8. 7/8 + ( 1/8 + 1/9 ) 9. 9 × 5/6 + 5/6 10. 3/4 × 8/9 - 1/3 11. 7 × 5/49 + 3/14 12. 6 ×( 1/2 + 2/3 ) 13. 8 × 4/5 + 8 × 11/5 14. 31 × 5/6 – 5/6 15. 9/7 - ( 2/7 – 10/21 ) 16. 5/9 × 18 – 14 × 2/7 17. 4/5 × 25/16 + 2/3 × 3/4 18. 14 × 8/7 – 5/6 × 12/15 19. 17/32 – 3/4 × 9/24 20. 3 × 2/9 + 1/3 21. 5/7 × 3/25 + 3/7 22. 3/14 ×× 2/3 + 1/6 23. 1/5 × 2/3 + 5/6 24. 9/22 + 1/11 ÷ 1/2 25. 5/3 × 11/5 + 4/3 26. 45 × 2/3 + 1/3 × 15 27. 7/19 + 12/19 × 5/6 28. 1/4 + 3/4 ÷ 2/3 29. 8/7 × 21/16 + 1/2 30. 101 × 1/5 – 1/5 × 21 31.50+160÷40 (58+370)÷(64-45) 32.120-144÷18+35 33.347+45×2-4160÷52 34(58+37)÷(64-9×5) 35.95÷(64-45) 36.178-145÷5×6+42 420+580-64×21÷28 37.812-700÷(9+31×11) (136+64)×(65-345÷23) 38.85+14×(14+208÷26) 39.(284+16)×(512-8208÷18) 40.120-36×4÷18+35 41.(58+37)÷(64-9×5) 42.(6.8-6.8×0.55)÷8.5 43.0.12× 4.8÷0.12×4.8 44.(3.2×1.5+2.5)÷1.6 (2)3.2×(1.5+2.5)÷1.6 45.6-1.6÷4= 5.38+7.85-5.37= 46.7.2÷0.8-1.2×5= 6-1.19×3-0.43= 47.6.5×(4.8-1.2×4)= 0.68×1.9+0.32×1.9 48.10.15-10.75×0.4-5.7 49.5.8×(3.87-0.13)+4.2×3.74 50.32.52-(6+9.728÷3.2)×2.5 51.[(7.1-5.6)×0.9-1.15] ÷2.5 52.5.4÷[2.6×(3.7-2.9)+0.62] 53.12×6÷(12-7.2)-6 (4)12×6÷7.2-6 102×4.5 7.8×6.9+2.2×6.9 5.6×0.25 8×(20-1.25) 1)127+352+73+44 (2)89+276+135+33 (1)25+71+75+29 +88 (2)243+89+111+57 9405-2940÷28×21 920-1680÷40÷7 690+47×52-398 148+3328÷64-75 360×24÷32+730 2100-94+48×54 51+(2304-2042)×23 4215+(4361-716)÷81 (247+18)×27÷25 36-720÷(360÷18) 1080÷(63-54)×80 (528+912)×5-6178 8528÷41×38-904 264+318-8280÷69 (174+209)×26- 9000 814-(278+322)÷15 1406+735×9÷45 3168-7828÷38+504 796-5040÷(630÷7) 285+(3000-372)÷36 1+5/6-19/12 3x(-9)+7x(-9 (-54)x1/6x(-1/3) 1.18.1+(3-0.299÷0.23)×1 2.(6.8-6.8×0.55)÷8.5 3.0.12× 4.8÷0.12×4.8 4.(3.2×1.5+2.5)÷1.6 (2)3.2×(1.5+2.5)÷1.6 5.6-1.6÷4= 5.38+7.85-5.37= 6.7.2÷0.8-1.2×5= 6-1.19×3-0.43= 7.6.5×(4.8-1.2×4)= 0.68×1.9+0.32×1.9 8.10.15-10.75×0.4-5.7 9.5.8×(3.87-0.13)+4.2×3.74 10.32.52-(6+9.728÷3.2)×2.5 11.[(7.1-5.6)×0.9-1.15] ÷2.5 12.5.4÷[2.6×(3.7-2.9)+0.62] 13.12×6÷(12-7.2)-6 14.12×6÷7.2-6 15.33.02-(148.4-90.85)÷2.5 7×(5/21+9/714) a^3-2b^3+ab(2a-b) =a^3+2a^2b-2b^3-ab^2 =a^2(a+2b)-b^2(2b+a) =(a+2b)(a^2-b^2) =(a+2b)(a+b)(a-b) 2. (x^2+y^2)^2-4y(x^2+y^2)+4y^2 =(x^2+y^2-2y)^2 3. (x^2+2x)^2+3(x^2+2x)+x^2+2x+3 =(x^2+2x)^2+4(x^2+2x)+3 =(x^2+2x+3)(x^2+2x+1) =(x^2+2x+3)(x+1)^2 4. (a+1)(a+2)+(2a+1)(a-2)-12 =a^2+3a+2+2a^2-3a-2-12 =3a^2-12 =3(a+2)(a-2) 5. x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2 =[x(y+z)-y(x-z)]^2 =(xz+yz)^2 =z^2(x+y)^2 6. 3(a+2)^2+28(a+2)-20 =[3(a+2)-2][(a+2)+10] =(3a+4)(a+12) 7. (a+b)^2-(b-c)^2+a^2-c^2 =(a+b)^2-c^2+a^2-(b-c)^2 =(a+b+c)(a+b-c)+(a+b-c)(a-b+c) =(a+b-c)(a+b+c+a-b+c) =2(a+b-c)(a+c) 8. x(x+1)(x^2+x-1)-2 =(x^2+x)(x^2+x-1)-2 =(x^2+x)^2-(x^2+x)-2 =(x^2+x-2)(x^2+x+1) =(x+2)(x-1)(x^2+x+1) 写完一遍后再别这些题写一遍,以此类推,老师们看作业都是一看而过不会一个一个批的。
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1、(X+4)平方=5(x+4)
2、(x+1)平方=4x
3、(x+3)平方=(1-2x)平方
4、2x平方-10x=3
5、(x+5)平方=16
6、2(2x-1)-x(1-2x)=0
7、x平方=64
8、5x平方-5分之二=0
9、8(3-x)平方-72
10、3x(x+2)=5(x+2)
ll、(1-3y)平方+2(3y-1)=0
12、x平方+2x+3=0
13、x平方+6x-5=0
14、x平方-4x+3=0
15、x平方-2x-1=0
16、2x平方+3x+1=0
17、3x平方+2x-1=0
18、(3x-2)平方=(2x-3)平方
19、(3x+2)(x+3)=x+14
20、2(x-3)平方=x平方=x平方-9
21、(2x-1)平方+3(2x-1)+2=0
2、(x+1)平方=4x
3、(x+3)平方=(1-2x)平方
4、2x平方-10x=3
5、(x+5)平方=16
6、2(2x-1)-x(1-2x)=0
7、x平方=64
8、5x平方-5分之二=0
9、8(3-x)平方-72
10、3x(x+2)=5(x+2)
ll、(1-3y)平方+2(3y-1)=0
12、x平方+2x+3=0
13、x平方+6x-5=0
14、x平方-4x+3=0
15、x平方-2x-1=0
16、2x平方+3x+1=0
17、3x平方+2x-1=0
18、(3x-2)平方=(2x-3)平方
19、(3x+2)(x+3)=x+14
20、2(x-3)平方=x平方=x平方-9
21、(2x-1)平方+3(2x-1)+2=0
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