Question

giúp mình giải mấy bài này nhé:

a) \(\frac{298}{719}:\left(\frac{1}{4}+\frac{1}{12}-\frac{1}{3}\right)-\frac{2011}{2012}\)                                      b)\(\frac{27.18+27.103-120.27}{15.33+33.12}\)

2. rút gọn : B=\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{20}\right)\)

Answer 1

\(\frac{27.\left(18+103-120\right)}{33.\left(15+12\right)}\)=\(\frac{27.1}{33.27}\)=\(\frac{1}{33}\)

mik dang ban moi giai duoc mot bai ha, sorry

Answer 2

k biet

Answer 3

\(\frac{27\cdot18\cdot27\cdot103-102\cdot27}{15\cdot33+33\cdot12}\)

=\(\frac{27\cdot\left(18+103-102\right)}{33\cdot\left(15+12\right)}\)

=\(\frac{27\cdot19}{33\cdot27}\)

=\(\frac{19}{33}\)

Answer 4

2.(1-1/2).(1-1/3).(1-1/4)....(1-1/20)

=1/2.2/3.3/4...19/20

=1/20