\(\text{Rút gọn BT .Ta dc:}\)

\(\frac{3}{16}+1=\frac{19}{16}\)
 

=6427,341346 nha bn

\(\frac{121212}{646464}+\frac{154.42+34}{156.42-50}=\frac{12}{64}+\frac{154.42+34}{154.42+84-50}=\frac{3}{16}+\frac{154.42+34}{154.42+34}=\frac{3}{6}+1=\frac{9}{6}=\frac{3}{2}\)

\(\frac{121212}{151515}+\frac{121212}{353535}+\frac{121212}{636363}+\frac{121212}{999999}\)

= \(\frac{12.10101}{15.10101}+\frac{12.10101}{35.10101}+\frac{12.10101}{63.10101}+\frac{12.10101}{99.10101}\)

= \(\frac{12}{15}+\frac{12}{35}+\frac{12}{63}+\frac{12}{99}\)

= \(\frac{12}{3.5}+\frac{12}{5.7}+\frac{12}{7.9}+\frac{12}{9.11}\)

= \(6.\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\right)\)

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

= \(6.\left(\frac{1}{3}-\frac{1}{11}\right)\)

= \(6.\frac{8}{33}\)

= \(\frac{16}{11}\)

a = 36

b=149/63

thanks

c, Dãy c có số số hạng là :

( 35 - 26 ) : 1 + 1 = 10 ( số hạng )

Tổng của dãy số trên là :

( 35 + 26 ) . 10 : 2 = 305

Vậy dãy c có tổng là 305

d,  ko bít làm

k mk nhé, thanks

c) (26+35)+(27+34)+(28+33)+(29+32)+(30+31)=61+61+61+61+61=61.5=305

d)  Ta có công thức 1 mũ 2 + 2 mũ 2 +3 mũ 2+...n  mũ 2=n.(n+1).(2n+1)/6

Áp dụng vào ta có 1 mũ 2 + 2 mũ 2+ 3 mũ 2+..100 mũ 2 =  100.(100+1) ( 2.100+1)/6= 100.101.201/6=338350

" /" là dấu gạch ngang phân số nhé.

=\(70\left(\frac{121212}{565656}+\frac{121212}{727272}+\frac{121212}{909090}\right)\)

=\(70\left(\frac{3.40404}{14.40404}+\frac{121212}{6.121212}+\frac{2.60606}{15.60606}\right)\)

=\(70\left(\frac{3}{14}+\frac{1}{6}+\frac{2}{15}\right)\)

=\(70.\frac{18}{35}=38\)

121212x121212=14692348944

k mình nha !

121212 x 121212 = 14692348944

14692348944

Ta có \(70\left(\frac{121212}{565656}+\frac{121212}{727272}+\frac{121212}{909090}\right)\)

\(=70\left(\frac{3\cdot40404}{14\cdot40404}+\frac{121212}{121212\cdot6}+\frac{2\cdot60606}{15\cdot60606}\right)\)

\(=70\left(\frac{3}{14}+\frac{1}{6}+\frac{2}{15}\right)\)

\(=70\cdot\frac{18}{35}=36\)