Question

\(\dfrac{15x8-10x7}{5x6+20x3}\)

Tính nhanh:

Answer 1

\(\dfrac{15x8-10x7}{5x6+20x3}=\dfrac{5x\left(3x8-2x7\right)}{5x\left(6+4x3\right)}=\dfrac{24-14}{18}=\dfrac{10}{18}=\dfrac{5}{9}\)

Answer 2

\(=\dfrac{5x^7\left(x-2\right)}{5x^3\left(x^2-4\right)}=\dfrac{x^4\left(x-2\right)}{\left(x-2\right)\left(x+2\right)}=\dfrac{x^4}{x+2}\)

Answer 3

`(15xx8-10xx7)/(5xx6+20xx3)`

`=(5xx3xx8-5xx2xx7)/(5xx6+5xx4xx3)`

`=(5xx24-5xx14)/(5xx6+5xx12)`

`=(5xx(24-14))/(5xx(6+12))`

`=10/(18)`

`=5/9`