八上数学题50道基础计算题含答案

八上数学题50道基础计算题含答案一、

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

二、

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.

4.

(4√5+√20)×(√8+4√2)

=6√5×6√2

=36√10

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) 66x+17y=3967

25x+y=1200

答案：x=48 y=47

(2) 18x+23y=2303 74x-y=1998

答案：x=27 y=79 (3) 44x+90y=7796 44x+y=3476

答案：x=79 y=48 (4) 76x-66y=4082 30x-y=2940

答案：x=98 y=51 (5) 67x+54y=8546 71x-y=5680

答案：x=80 y=59 (6) 42x-95y=-1410 21x-y=1575

答案：x=75 y=48 (7) 47x-40y=853 34x-y=2006

答案：x=59 y=48 (8) 19x-32y=-1786 75x+y=4950

答案：x=66 y=95 (9) 97x+24y=7202

58x-y=2900

答案：x=50 y=98 (10) 42x+85y=6362 63x-y=1638

答案：x=26 y=62 (11) 85x-92y=-2518 27x-y=486

答案：x=18 y=44 (12) 79x+40y=2419 56x-y=1176

答案：x=21 y=19 (13) 80x-87y=2156 22x-y=880

答案：x=40 y=12 (14) 32x+62y=5134 57x+y=2850

答案：x=50 y=57 (15) 83x-49y=82 59x+y=2183

答案：x=37 y=61 (16) 91x+70y=5845 95x-y=4275

答案：x=45 y=25 (17) 29x+44y=5281 88x-y=3608

答案：x=41 y=93 (18) 25x-95y=-4355 40x-y=2000

答案：x=50 y=59 (19) 54x+68y=3284 78x+y=1404

答案：x=18 y=34 (20) 70x+13y=3520 52x+y=2132

答案：x=41 y=50 (21) 48x-54y=-3186 24x+y=1080

答案：x=45 y=99 (22) 36x+77y=7619 47x-y=799

答案：x=17 y=91 (23) 13x-42y=-2717 31x-y=1333

答案：x=43 y=78