9700

TICK CHO MIK VỚI!

80*33+97*33+34*97+33*17

=33*(80+97+17)+34*97

=33*194+34*97

=33*97*2+34*97

=97*(33*2+34)

=97*100

=9700

tik mik nha bn

  80*33+97*33+34*97+33*17

=33*(80+17)+97*(33+34)

=33*97+97*67

=97*(33+67)

=97*100=9700

\(\frac{1}{3}+\frac{13}{15}+\frac{33}{35}+\frac{61}{63}+\frac{97}{99}\)\(+\frac{141}{143}\)

\(=\left(1-\frac{2}{3}\right)+\left(1-\frac{2}{15}\right)\)\(+\left(1-\frac{2}{35}\right)+\left(1-\frac{2}{63}\right)\)\(+\left(1-\frac{2}{99}\right)+\left(1-\frac{2}{143}\right)\)

\(=\left(1+1+1+1+1+1\right)-\)\(\left(\frac{2}{3}+\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}+\frac{2}{143}\right)\)

\(=6-\)\(\left(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}+\frac{2}{11\times13}\right)\)

\(=6-\)\(\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}\right)\)

\(=6-\left(1-\frac{1}{13}\right)\)

\(=6-\frac{12}{13}\)

\(=\frac{66}{13}\)

a)

Ta có : ( 1 + 2 + 3 + ... + 99)

Số số hạng là:       ( 99 - 1 )  : 1 + 1 = 100

Tổng là:                 ( 99 + 1 ) x 100 : 2 = 5000

=> 5000 x ( 13  - 12 - 1 ) x 15

=> 5000 x 10 x 15

=> 50000 x 15

=> 750000

Ko muốn vt nx :))

97 x 99

= 97 x (100 - 1)

= 97 x 100 - 97

= 9700 - 97

= 9603

a) 97x99

=(99-2)x99

=99x99-2x99

=9801-198

=9603.

K nhé các bạn ơi.

\(97\times99\)

\(=\left(99-2\right)\times99\)

\(=99\times99-2\times99\)

\(=9603\)

bài 15 băng 72/13 bạn nha hoc ngu

giải kiểu gì vậy. ghi vào vở như nào

trả lời đầy đủ ra nhé các bn !

=[(99-1):2+1]x(99+1)x[45x(3-2-1)]

=(50x100)x(45x0)

=5000x0

=0

=0 nha bn

năm hok mới mk chúc bn hok tốt 

a) \(33\times4+5\times33+33\times3+33-99=33\times4+5\times33+33\times3+33\times1-33\times3\)

\(=33\times\left(4+5+3+1-3\right)=33\times10=330\)

b) \(256+347+453-147-56-253=\left(256-56\right)+\left(347-147\right)+\left(453-253\right)\)

\(=200+200+200=600\)

97x99=97x(100-1)=97x100-97=9700-97=9603 nhé

\(97.99\\ =97.\left(100-1\right)\\ =9700-97\\ =9603.\)

Ta có : 

99.97 = (100 - 1) . 97 

=100.97 - 1.97

=9700 - 97

9=603

đề :

= 1/100 - (1 / 100.99 +1/99.98 + ...+ 1/3.2 +1/2.1 ) 

=1/100 - (1 /1.2 +1/ 2.3 +...+ 1/ 98.99 +1 / 99.100)

=1/100 -( 1- 1/ 2 +1/2 -1/3 +...+1/98 -1/99 +1/99 -1/100)

=1/100 - ( 1- 1/100)

=1/100 - 99 /100

= -98/100

= -49 /50