\(\dfrac{121212}{353535}+-\dfrac{2323}{4242}\)

\(=\dfrac{12}{35}+-\dfrac{23}{42}\)

\(=-\dfrac{43}{210}\)

\(=\dfrac{12}{35}-\dfrac{23}{42}=\dfrac{72-115}{210}=\dfrac{-43}{210}\)

121212/151515+a/5

=121212/151515+30303/151515

=                   1

     k nhé

\(\left(\frac{151515}{60606}+\frac{151515}{121212}+\frac{151515}{202020}+\frac{151515}{303030}+\frac{151515}{242424}\right)\cdot\frac{28}{12}\)

\(=\left(\frac{5}{2}+\frac{5}{4}+\frac{3}{4}+\frac{1}{2}+\frac{5}{8}\right)\cdot\frac{28}{12}\)

\(=\left[\left(\frac{5}{2}+\frac{1}{2}\right)+\left(\frac{5}{4}+\frac{3}{4}\right)+\frac{5}{8}\right]\cdot\frac{28}{12}\)

\(=\left(3+2+\frac{5}{8}\right)\cdot\frac{28}{12}\)

\(=\left(5+\frac{5}{8}\right)\cdot\frac{28}{12}\)

\(=\frac{45}{8}\cdot\frac{28}{12}\)

\(=\frac{105}{8}\)

131313/151515+131313/353535+131313/636363+131313/999999=13/15+13/35+13/63+13/99

=52/33=1/19/33

​DUYỆT NHÉ

thuy hang beautyful lam chuan

= 13/15 + 13/35 + 13/63 + 13/99
= 13/ 3×5 + 13/5×7 + 13/7×9 + 13/9×11
= 13 x 1/2( 1/3 – 1/5 + 1/5 – 1/7 +1/7 – 1/9 +1/9 – 1/11)
= 13/2 x ( 1/3 – 1/11)
= 13/2 x 8/33 = 104/66=52/33

\(D=\frac{13}{15}+\frac{13}{35}+\frac{13}{63}+\frac{13}{99}\)

\(D=\frac{13}{3}\times5+\frac{13}{5}\times7+\frac{13}{7}\times9+\frac{13}{9}\times11\)

\(D=13\times\frac{1}{2}\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\right)\)

\(D=\frac{13}{2}\times\left(\frac{1}{3}-\frac{1}{11}\right)\)

\(D=\frac{13}{2}\times\frac{8}{33}=\frac{104}{66}=\frac{52}{33}\)

\(D=\frac{52}{33}\)

(131313/151515+ 131313/353535+131313/636363+131313/999999)*33

=(13/15+13/35+13/63+13/99)*33

=52/33*33

=52

a)121212/151515 + 1414/2121

= 4/5                     +    2/3

= 22/15

a) \(\frac{121212}{151515}+\frac{1414}{2121}=\frac{12}{15}+\frac{14}{21}=\frac{12}{15}+\frac{2}{3}=\frac{12}{15}+\frac{10}{15}=\frac{22}{15}\)

Phần b