Question

[Tran Thuy Linh]

tinh gia tri cua bieu thuc:

A = \(\frac{55}{11.16}+\frac{55}{16.21}+\frac{55}{21.26}+\frac{55}{26.31}+\frac{55}{31.36}+\frac{55}{36.41}\)

* dau cham la dau nhan nhe

Answer 1

[Nguyễn Ngọc Anh Minh]

\(A=11x\left(\frac{5}{11x16}+\frac{5}{16x21}+\frac{5}{21x26}+\frac{5}{26x31}+\frac{5}{31x36}+\frac{5}{36x41}\right)\)

\(A=11x\left(\frac{16-11}{11x16}+\frac{21-16}{16x21}+\frac{26-21}{21x26}+...+\frac{41-36}{36x41}\right)\)

\(A=11x\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+...+\frac{1}{36}-\frac{1}{41}\right)\)

\(A=11x\left(\frac{1}{11}-\frac{1}{41}\right)=11x\frac{30}{11x41}=\frac{30}{41}\)

Answer 2

[Hồ Thu Giang]

A=\(\frac{55}{11.16}+\frac{55}{16.21}+...+\frac{55}{36.41}\)

A=\(11\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+...+\frac{1}{36}-\frac{1}{41}\right)\)

A=\(11\left(\frac{1}{11}-\frac{1}{41}\right)\)

A=\(11.\frac{30}{451}\)

A=\(\frac{30}{41}\)