giải hộ e bai 2 zới. e cảm ơn

Đáp án: 2. a)$\frac{4.15}{3.8}$ 

 = $\frac{4.3.5}{3.4.2}$ 

= $\frac{5}{2}$ 

b) $\frac{2.5.13}{65.6}$ 

= $\frac{2.(5.13)}{65.2.3}$ 

= $\frac{2.65}{65.2.3}$

= $\frac{1}{3}$ 

c) $\frac{9.6-6.4}{15.7-5.15}$ 

= $\frac{6.(9-4)}{15.(7-5)}$ 

= $\frac{2.3.5}{5.3.2}$ 

= 1

d) $\frac{2020-4}{4019+13}$ 

= $\frac{2016}{4032}$ 

= $\frac{2016}{2016.2}$ 

= $\frac{1}{2}$ 

e) $\frac{191919}{202020}$ 

= $\frac{190000+1900+19}{200000+2000+20}$ 

= $\frac{19.(10000+100+1)}{20.(10000+100+1)}$ 

= $\frac{19}{20}$ 

f) $\frac{x+2x+3x+4x}{x-2x+3x-4x}$ 

= $\frac{x.(1+2+3+4)}{x.(1-2+3-4)}$ 

= $\frac{10}{-2}$ 

= $\frac{2.5}{-2}$ 

= -5