\(A=\frac{3}{4}\cdot\frac{8}{9}\cdot\frac{15}{16}\cdot....\cdot\frac{960}{961}\)

\(=\frac{1.3}{2.2}\cdot\frac{2.4}{3.3}\cdot\frac{3.5}{4.4}\cdot.....\cdot\frac{30.32}{31.31}\)

\(=\frac{\left(1.2.3....30\right)\left(3.4.5....32\right)}{\left(2.3.4....31\right)\left(2.3.4...31\right)}\)

\(=\frac{32}{31.2}=\frac{32}{62}=\frac{16}{31}\)

\(A=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}....\frac{960}{961}\)

\(\Rightarrow A=\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}.....\frac{30.32}{31.31}\)

\(\Rightarrow A=\frac{1.2.3....30}{2.3.4....31}.\frac{3.4.5.....32}{2.3.4.....31}\)

\(\Rightarrow A=\frac{1}{31}.\frac{32}{2}=\frac{16}{31}\)

\(A=\dfrac{3}{4}\cdot\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot...\cdot\dfrac{960}{961}\\ =\dfrac{1}{2}\cdot\dfrac{3}{2}\cdot\dfrac{2}{3}\cdot\dfrac{4}{3}\cdot\dfrac{3}{4}\cdot\dfrac{5}{4}\cdot...\cdot\dfrac{30}{31}\cdot\dfrac{32}{31}\\ =\dfrac{1}{2}\cdot\dfrac{32}{31}\\ =\dfrac{16}{31}\)

Tìm y:

-y:1/2-5/2=4+1/2

-y:1/2 = 4+1/2+5/2

-y:1/2 = 7

-y = 7.2

y = -14

Vậy y = -14

@.@                   

Người ta hỏi cái gì thế?

nói mk trả lời cho

16.2 + 8.4 + 32.3 \\
= 32 + 8 . 4 + 96 \\
= 40 + 100 \\
= 140

Bài làm:

Ta có: \(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.....\frac{2499}{2500}\)

\(=\frac{1.3}{2^2}.\frac{2.4}{3^2}.\frac{3.5}{4^2}.....\frac{49.51}{50^2}\)

\(=\frac{\left(1.2.3.....49\right).\left(3.4.5.....51\right)}{\left(2.3.4.....50\right).\left(2.3.4.....50\right)}\)

\(=\frac{51}{50.2}\)

\(=\frac{51}{100}\)

\(A=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}...\frac{899}{900}=\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}....\frac{29.31}{30.30}=\frac{1.3.2.4.3.5...29.31}{2.2.3.3.4.4...30.30}=\frac{\left(1.2.3...29\right)\left(3.4.5...31\right)}{\left(2.3.4...30\right)\left(2.3.4...30\right)}\)

\(=\frac{1.31}{30.2}=\frac{31}{60}\)

\(\frac{3}{4}\cdot\frac{8}{9}\cdot\frac{15}{16}\cdot....\cdot\frac{9999}{10000}\)  Dạng tổng quát:  

Bạn dùng máy tính casio bấm là ra kết quả liền. Kết quả là: \(\frac{101}{200}\)