Question

tính nhanh 

a :

7*8*9*10/9*8*7*12                                                                                                                                                                             b:

3*145+3*55/6*215+6*85                     

Answer 1

a:

\(\frac{7x8x9x10}{9x8x7x12}\)

= \(\frac{7x8x9x2x5}{9x8x7x2x6}\)

= \(\frac{5}{6}\)

b: \(\frac{3x145+3x55}{6x215+6x85}\)

= \(\frac{3x\left(145+55\right)}{6x\left(215+85\right)}\)

= \(\frac{3x200}{6x300}\)

= \(\frac{3x100x2}{2x3x3x100}\)

= \(\frac{1}{3}\)

Answer 2

a)   \(\frac{7\times8\times9\times10}{9\times8\times7\times12}\)

\(=\frac{10}{12}=\frac{5}{6}\)

b)  \(\frac{3\times145+3\times55}{6\times215+6\times85}\)

\(=\frac{3\left(145+55\right)}{6\left(215+85\right)}\)

\(=\frac{3\times200}{6\times300}\)

\(=\frac{1}{3}\)

Answer 3

Đáp án :5/6

Answer 4

b) Đápán :1/3