Question

[Tạ Thu Hà]

Bài 1: Tính nhanh

c) 35. 18 – 5. 7. 28

d) 24. (16 – 5) – 16. (24 - 5) 

e) 29. (19 – 13) – 19. (29 – 13)

g) 31. (-18) + 31. ( - 81) – 31

h) (-12).47 + (-12). 52 + (-12)

k) 13.(23 + 22) – 3.(17 + 28)

m) -48 + 48. (-78) + 48.(-21)

n) 135. (171 – 123) – 171. (135  - 123)

p) - (-2009 + 97) – 74. (-18) + 74. (-118) – 2009 – 3

Bài 2: Tìm số nguyên x

a/-2x – (x – 17) = 34 – (-x + 25)

b/17x – ( -16x – 37) = 2x + 43

c/-2x –3. (x – 17) = 34 – 2(-x + 25)

d/ ( x – 1)³ – 2 = -10

Bài 3: Chứng minh đẳng thức

1/     (a – b + c) – (a + c) = -b

2/      (a + b) – (b – a) + c = 2a + c

3/     - (a + b – c) + (a – b – c) = -2b

4/     a(b + c) – a(b + d) = a(c – d)

5/     a(b – c) + a(d + c) = a(b + d)

     6/ a(b – c) – a(b + d) = -a( c + d)

     7/ (a + b)( c + d) – (a + d)( b + c) = (a – c)(d –b)

Answer 1

[bùi văn mạnh]

a, =-25.21.4.(-3).(-1)

=-25.4.21.4

=-100.21.4

=-2100.4

=-8400

b, =-125.67.(-8).1

=-125.(-8).67

=1000.67

=67000

c, =35.18-35.28

=35.(18-28)

=35.(-10)

=-350

d, =24.11-16.24+16.5

=24.(11-16)+16.5

=24.(-5)+16.5

=5.(-24+16)

=5.(-8)

=-40

e, =29.6-19.29+19.13

=29.(6-19)+19.13

=29.(-13)+19.13

=13.(-29+19)

=13.(-10)

=-130

Answer 2

[Tạ Thu Hà]

mk bo sung:

bai 1:

a) (-25).21. (-2)².(-l-3l).(-1)²ⁿ⁺¹ (n thuoc N^*)

b) (-5)³. 67.(-l-2 mu 3l (-1)²ⁿ(n thuoc N^*)

bai 2:

e) {-3x +2.[45-x-3.(3x+7)-2x]­+4}=55