TA CÓ:

a; 1313/2121=13/21    165165/143143=165/143       424242/151515=42/15

=> 13/21 x 165/143 x 42/15=13 x 165 x 42/21 x 143 x 15=22/11=2

b,1995/1995 x 19961996/19931993 x 199319931993/199519951995

=1 x 1996/1993 x 1993/1995

=1 x 1996/1995

=1996/1995

a, 1313/2121 x 165165/143143 x 424242/151515

=13/21 x 165/143 x 13/5

=2

\(\frac{1995}{1996}.\frac{19961996}{19311931}.\frac{19311931}{19951995}=\frac{1995}{1996}.\frac{1996}{1931}.\frac{1931}{1995}=1\)

\(\frac{1313}{2121}.\frac{165165}{143143}.\frac{424242}{151515}=\frac{13}{21}.\frac{165}{143}.\frac{42}{15}=\frac{1}{1}.\frac{11}{11}.\frac{2}{1}=2\)

a)=1

b)=2

ủng hộ mk nha

\(\frac{1313}{2121}\)x\(\frac{165165}{143143}\)x\(\frac{424242}{151515}\)

=\(\frac{13x101}{21x101}\)X\(\frac{165x1001}{143x1001}\)X\(\frac{42x10101}{15x10101}\)

=\(\frac{13}{21}\)x\(\frac{165}{143}\)x\(\frac{42}{15}\)

=\(\frac{13}{21}\)x\(\frac{15}{13}\)x\(\frac{14}{5}\)

=\(\frac{13x15x14}{21x13x5}\)

=2

Ghớm thế Lê Khương Duy

Kết quả bằng 0 (Biến đổi ngoặc cuối cùng =0)

bài này tớ làm rồi nhưng quên cách làm

/ la phan hay chia day

dễ quá bạn ơi,kiến thức cơ bản

\(\frac{3}{2\times5}+\frac{3}{5\times8}+\frac{3}{8\times11}+\frac{3}{11\times14}\)

\(=\frac{5-2}{2\times5}+\frac{8-5}{5\times8}+\frac{11-8}{8\times11}+\frac{14-11}{11\times14}\)

\(=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}\)

\(=\frac{1}{2}-\frac{1}{14}=\frac{7}{14}-\frac{1}{14}=\frac{6}{14}=\frac{3}{7}\)