=(100+121+144):(169+196)

=365:365

=1

\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{2352}+\frac{1}{2450}\\ \)

\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{49.50}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{49}-\frac{1}{50}\)

\(=1-\frac{1}{50}\)

\(=\frac{49}{50}\)

S=1/2+1/6+...............+1/2450

S=1/1.2+1/2.3+............+1/49.50

S=1-1/2+1/2-1/3+..........+1/49-1/50

S=1-1/50

S=49/50

S=1/2+1/6+...............+1/2450

S=1/1.2+1/2.3+............+1/49.50

S=1-1/2+1/2-1/3+..........+1/49-1/50

S=1-1/50

S=49/50

S=1/2+1/6+1/12+1/20+...+1/2352+1/2450

S=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+...+1/48-1/49+1/49-1/50

S=1-1/50

S=49/50

Vậy S=49/50

\(=>S=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{48.49}+\frac{1}{49.50}\)

\(=>S=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+..+\frac{1}{48}-\frac{1}{49}+\frac{1}{49}-\frac{1}{50}=\frac{1}{1}-\frac{1}{50}=\frac{49}{50}\)

vậy S=49/50

49/50 nha bn

câu 1: tính lần lượt là dc

câu 2:

\(\frac{1}{2}+\frac{1}{6}+...+\frac{1}{2450}\)

\(=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{49.50}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{49}-\frac{1}{50}\)

\(=1-\frac{1}{50}\)

\(=\frac{49}{50}\)

lên lời giải hay ý

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{2450}+\frac{1}{2550}\)

\(A=\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{49x50}+\frac{1}{50x51}\)

\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{49}-\frac{1}{50}+\frac{1}{50}-\frac{1}{51}\)

\(A=1-\frac{1}{51}=\frac{50}{51}\)

50/51

1²+1 + 2²+2 + 3²+3 + 4²+4 + ... + 48²+48 + 49²+49 + 50²+50

= (1+2+3+4+..+48+49+50) +(1²+2²+3²+4²+...+48²+49²+50²)

Đến đay bạn tự tính nha

50/51

dap an da dung roi

A=1/1x2+1/2x3+1/3x4+1/4x5+...+1/49x50+1/50x51

A=2-1/1x2+3-2/2x3+4-3/3x4+...+50-49/49x50+51-50/50x51

A=1-1/2+1/2-1/3+1/3+1/4+...-1/49+1/49-1/50+1/50-1/51

A=1-1/51

A=51/51-1/51

A=50/51

tick nha