Đáp án+Giải thích các bước giải:

 `1)5xy.(-2bx^{2}y)`

`=[5.(-2b)].(x.x^{2}).(y.y)`

`=-10bx^{3}y^{2}`

`2)(-4/5 ab^{2}c).(-20a^{4}bx)`

`=[(-4/5). (-20)].(a.a^{4}).(b^{2}.b).c.x`

`=16a^{5}b^{3}cx`

`3)2^{3}bc. 1/4 a^{2}bc^{3}`

`=(2^{3}. 1/4).a^{2}. (b.b).(c.c^{3})`

`=2 a^{2}b^{2}c^{4}`

`4)a^{3}b^{3}a^{2}b^{2}c`

`=(a^{3}.a^{2}).(b^{3}.b^{2}).c`

`=a^{5}b^{5}c`

`5)2ab. 4/3 a^{2}b^{4}.7abc`

`=(2. 4/3. 7).(a.a^{2}.a).(b.b^{4}.b).c`

`=56/3 a^{4}b^{6}c`

`6) 2x.(-4xy).(8x^{2}y^{3})`

`=[2.(-4).8].(x.x.x^{2}).(y.y^{3})`

`=-64x^{4}y^{4}`

`7)(1/2 x^{2}y).(2^{3}xy)`

`=[(1/2)^{2}.(x^{2})^{2}.y^{2}].(8xy)`

`=(1/4 x^{4}y^{2}).(8xy)`

`=(1/4. 8).(x^{4}.x).(y^{2}.y)`

`=2x^{5}y^{3}`

`8)(2x^{2})^{2}.(-3y^{3}).(-5xz)^{2}`

`=(2x^{2})^{2}.(5xz)^{2}.(-3y^{3})`

`=(2x^{2}.5xz)^{2}.(-3y^{3})`

`=(10x^{3}z)^{2}.(-3y^{3})`

`=[10^{2}.(x^{3})^{2}.z^{2}].(-3y^{3})`

`=(100x^{6}z^{2}).(-3y^{3})`

`=[100.(-3)].x^{6}.y^{3}.z^{2}`

`=-300x^{6}y^{3}z^{2}`