Question

[Nguyễn Thị Thủy]

TÍNH:        A=1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8

                B=3/12+3/20+3/30+3/42+3/56+3/72+3/90+3/110+3/132

                C=(25.73+25.27):60%-900+(1+3/7)-A/B

                D=A^2+300-C.(-12)+B.325%

Answer 1

[Thắng Nguyễn]

A=1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8

\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{7}-\frac{1}{8}\)

\(A=1-\frac{1}{8}\)

\(A=\frac{7}{8}\)

B=3/12+3/20+3/30+3/42+3/56+3/72+3/90+3/110+3/132

\(B=\frac{3}{3.4}+\frac{3}{4.5}+....+\frac{3}{11.12}\)

\(B=3\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{11}-\frac{1}{12}\right)\)

\(B=3\left(\frac{1}{3}-\frac{1}{12}\right)\)

\(B=3\times\frac{1}{4}\)

\(B=\frac{3}{4}\)

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