Tìm x, biết :

a) ( 3x + 9 ) . ( x - 10 ) = 0

b) ( x - 5 )³ = 88

c) ( - 8 ) . x = ( - 7 ) . ( - 6 ) - 2

Bài 4: Tính:

a) (5/2 + 1/3) : (1 - 2/3)

b) (5/2 - 1/3) x 9/2 - 6/7

Bài 5: Tính nhanh:

a) 254 x 399 - 145/254 + 399 x 253

b) 5932 + 6001 x 5931/5932 x  6001 - 69

1, 11.(2+4+6+8)+89.(2+4+6+8)

2, 18.(1+3+5+7)+82.(1+3+5+7)

3, 54.(5+10+15)+46.(15+10+5)

4, 39.(4+7+9)+(9+7+4).61

1, 36.37+12.38.3+18.25.2

2, 2.24.25+3.31.16+6.2.8.17

3, 15.360+150.2.25+1500

8.4.37 + 32 + 32.63