\(\frac{85-17+34}{51-102}\)

\(=\frac{17\left(5-1+2\right)}{51\left(1-2\right)}\)

\(=\frac{17.6}{51.\left(-1\right)}\)

\(=\frac{1.6}{3.\left(-1\right)}\)

\(=\frac{1.2}{1.\left(-1\right)}\)

\(=\frac{2}{-1}\)

\(=-2\)

-33/1/3

e tu lan sau nh dau gach can thn vao 

a) \(\frac{-28}{72}=\frac{-7}{18}\)

b) \(\frac{-75}{-105}=\frac{75}{105}=\frac{5}{7}\)

c) \(\frac{3.5.11.13}{33.35.37}=\frac{3.5.11.13}{3.11.5.7.37}=\frac{13}{7.37}=\frac{13}{259}\)

d) \(\frac{85-17+34}{51-102}=\frac{102}{-51}=-2\)

a) \(\frac{-28}{72}=\frac{\left(-28\right):4}{72:4}=\frac{-7}{18}\)

b) \(\frac{-75}{-105}=\frac{\left(-75\right):\left(-15\right)}{\left(-105\right):\left(-15\right)}=\frac{5}{7}\)

c) \(\frac{3.5.11.13}{33.35.37}=\frac{3.5.11.13}{11.3.5.7.37}=\frac{13}{7.37}=\frac{13}{259}\)

d) \(\frac{85-17+34}{51-102}=-2\)

                 72=18.     -105=105=7

C. 51; 68 nha bn

\(B\left(17\right)\in\left\{17;34;51;68;85;...\right\}\)

Mà B(17) >50, <70

\(\Rightarrow B\left(17\right)\in\left\{51;68\right\}\)

Chọn C

a. 3.5.11.13       3..5.11.13       13         13

   33.35.37   =  3.11.5.7.37 =   7.37   = 259

mình viết nó bị méo

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