17/25 nha bạn

Đề bài yêu cầu làm j z bn

8/9 x 15/16 x 24/25 x...x 2499/2500

=   \(\frac{2\times4}{3\times3}\times\frac{3\times5}{4\times4}\times\frac{4\times6}{5\times5}\times...\times\frac{49\times51}{50\times50}\)

=   \(\frac{2\times4\times3\times5\times4\times6\times...\times49\times51}{3\times3\times4\times4\times5\times5\times...\times50\times50}\)

= \(\frac{2\times51}{3\times50}\)

= \(\frac{17}{25}\)

\(\frac{8}{9}.\frac{15}{16}.\frac{24}{25}....\frac{2499}{2500}=\frac{8.15...2499}{9.16...2500}=\frac{2.4.3.5...49.51}{3.3.4.4...50.50}=\frac{\left(2.3.4...49.50\right).\left(4.5...49.51\right)}{\left(2.3.4...49.50\right).\left(3.4.5...49.50\right)}=\frac{51}{3.50}\)\(=\frac{17}{50}\)

HELLO, KẾT BẠN VỚI MÌNH NHÉ ^.^ !!!

A=2.4/3^2 . 3.5/4^2 . 4.6/5^2 ............ . 49.51/50^2

A=2/3-51/50

A=17/25.

Chúc bạn hok tốt.

Bài này cũng dễ ý mà, vô cùng đơn giản.........

Giải:

Ta có: \(A=\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}.....\dfrac{2499}{2500}.\)

\(=\dfrac{2.4}{3^2}.\dfrac{3.5}{4^2}.....\dfrac{49.51}{50^2}.\)

\(=\dfrac{\left(2.3.4.....49\right)\left(4.5.6.....51\right)}{\left(3.4.5.....50\right)\left(3.4.5.....50\right)}.\)

\(=\dfrac{2.51}{3.50}.\)

\(=\dfrac{17}{25}.\)

CHÚC BN HỌC TỐT!!! ^ _ ^

Đừng quên bình luận nếu bài mik sai nhé!!! - _ -

Còn nếu bài mik đúng thì nhớ tick mik để mik lấy SP nha!!! ^ - ^

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a=8/9+15/16+24/25+....+2499/2500

a=(1-1/9)+(1-1/16)+(1-1/25)+....+(1-1/2500)

a=1-1/9+1-1/16+1-1/25+....+1-1/2500

a=(1+1+...+1)-(1/9+1/16+1/25+....+1/2500)

A= 3^2-1/3.3 . 4^2-1/4.4 . 5^2-1/5.5 . ... 50^2-1/50.50 A= (3+1).(3-1).(4+1).(4-1).(5+1).(5-1). ... (50+1).(50-1) / 3.3.4.4.5.5. ... . 50.50 A=4.2.5.3.6.4. ... 51.49 / 3.3.4.4.5.5....50.50 A=(4.5.6. ... .51).(2.3.4. ... 49)/(3.4.5.... .50).(3.4.5.. ... 50) A= 51.2/3.50 A=17/25

Ta có:

\(A=\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}......\dfrac{2499}{2500}\)

= \(\dfrac{2.4}{3.3}.\dfrac{3.5}{4.4}.\dfrac{4.6}{5.5}......\dfrac{49.51}{50.50}\)

= \(\dfrac{2.4.3.5.4.6......49.51}{3.3.4.4.5.5......50.50}\)

= \(\dfrac{\left(2.3.4....49\right)\left(4.5.6....51\right)}{\left(3.4.5....50\right)\left(3.4.5....50\right)}\)

= \(\dfrac{2}{50}.\dfrac{51}{3}\) = \(\dfrac{17}{25}\)