a, = 113 x (54+45+1) = 113 x 100 = 11300

b, = (36+62) x (117-17) = 98 x 100 = 9800

k mk nha

11300

9800

h cho mk nha

63 x 113 + 36 x 113 + 113

= (63 + 36 + 1) x 113

= 100 x 113

= 11300

63 x 113 + 36 x 113 + 113

= 113 x ( 63 + 36 + 1 )

= 113 x 100

= 11 300

Ta có: \(\frac{1}{\left(2n+1\right)\left(2n+3\right)}-\frac{1}{\left(2n+3\right)\left(2n+5\right)}\)

\(=\frac{2n+5-\left(2n+1\right)}{\left(2n+1\right)\left(2n+3\right)\left(2n+5\right)}\)

\(=\frac{4}{\left(2n+1\right)\left(2n+3\right)\left(2n+5\right)}\)

=>\(\frac{1}{\left(2n+1\right)\left(2n+3\right)\left(2n+5\right)}=\frac14\left(\frac{1}{\left(2n+1\right)\left(2n+3\right)}-\frac{1}{\left(2n+3\right)\left(2n+5\right)}\right)\)

Do đó, ta có:

\(\frac{1}{1\cdot3\cdot5}=\frac14\left(\frac{1}{1\cdot3}-\frac{1}{3\cdot5}\right)\)

\(\frac{1}{3\cdot5\cdot7}=\frac14\left(\frac{1}{3\cdot5}-\frac{1}{5\cdot7}\right)\)

...

\(\frac{1}{25\cdot27\cdot29}=\frac14\left(\frac{1}{25\cdot27}-\frac{1}{27\cdot29}\right)\)

Do đó: \(\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}+\cdots+\frac{1}{25\cdot27\cdot29}=\frac14\left(\frac{1}{1\cdot3}-\frac{1}{3\cdot5}+\frac{1}{3\cdot5}-\frac{1}{5\cdot7}+\cdots+\frac{1}{25\cdot27}-\frac{1}{27\cdot29}\right)\)

\(=\frac14\left(\frac{1}{1\cdot3}-\frac{1}{27\cdot29}\right)\)

=>\(36\left(\frac{1}{1\cdot3\cdot5}+\frac{1}{3\cdot5\cdot7}+\cdots+\frac{1}{25\cdot27\cdot29}\right)=36\cdot\frac14\left(\frac{1}{1\cdot3}-\frac{1}{27\cdot29}\right)\)

=>\(\frac{36}{1\cdot3\cdot5}+\frac{36}{3\cdot5\cdot7}+\cdots+\frac{36}{25\cdot27\cdot29}=9\left(\frac13-\frac{1}{27\cdot29}\right)=3-\frac{1}{3\cdot29}=\frac{3\cdot3\cdot29-1}{3\cdot29}=\frac{260}{87}\)

\(\left(-133\right).36+45.\left(-133\right).\left(-133\right).19\)

a) 54x113+45x113+113                                          b)117x(36+62) -17x(62+36)
   =(54+45+1)x113                                                    =117x98-17x98
   = 100x113                                                            =(117-17)x98
   = 11300                                                                =100x98
                                                                               =9800

a,54 x 113 + 45 x 113 + 113

=(54 + 45 +1) x 113

=100 x 113 = 11300

13303 nha bạn tk mik nhé

13303 là kết quả của tớ

a)63x113+36x113+113

=113x(36+63+1)

=113x100

=11300

b)115x(36+62)-15x(62+36)

=115x98-15x98

=11270-1470

=9800

a,63.113+36.113+113

=63.113+36.113+113.1

=(63+36+1).113

=100.113

=11300

b,115.(36+62)-15.(62+36)

=115.98-15.98

=(115-15).98

=100.98

=9800

Đáp án là:c

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