Question

Tìm giá trị của biểu thức sau:

a)\(A=\frac{2}{3}+\frac{5}{6}:5-\frac{1}{18}.\left(-3\right)^2\)

b)\(B=3.\left\{5.\left[\left(5^2+2^3\right):11\right]-16\right\}+2015\)

c)\(C=\left(1+\frac{1}{1.3}\right)\left(1+\frac{1}{2.4}\right)\left(1+\frac{1}{3.5}\right).....\left(1+\frac{1}{2014.2016}\right)\)

Answer 1

https://dethihsg.com/de-thi-hoc-sinh-gioi-phong-gddt-hoang-hoa-2014-2015/

vào đây gợi ý nhé

k mik đi

@_@

Answer 2

đây nè

Answer 3

k mik nha

Answer 4

a) \(A=\frac{2}{3}+\frac{5}{6}:5-\frac{1}{18}:\left(-3\right)^2\)

    \(A=\frac{2}{3}+\frac{5}{6}.\frac{1}{5}-\frac{1}{18}:9\)

   \(A=\frac{2}{3}+\frac{1}{5}-\frac{1}{18}.\frac{1}{9}\)

   \(A=\frac{13}{15}-\frac{1}{162}\)

   \(A=\frac{702-5}{810}\)

   \(A=\frac{697}{810}\)

Vậy \(A=\frac{697}{810}\)

b) \(B=3.\left\{5.\left[\left(5^2+2^3\right):11\right]-16\right\}+2015\)

    \(B=3.\left\{5.\left[\left(25+8\right):11\right]-16\right\}+2015\)

    \(B=3.\left\{5.\left[33:11\right]-16\right\}+2015\)

    \(B=3.\left\{5.3-16\right\}+2015\)

    \(B=3.\left\{15-16\right\}+2015\)

    \(B=3.\left(-1\right)+2015\)

    \(B=\left(-3\right)+2015\)

    \(B=2012\)

Vậy \(B=2012\)

c) \(C=\left(1+\frac{1}{1.3}\right)\left(1+\frac{1}{2.4}\right)\left(1+\frac{1}{3.5}\right).......\left(1+\frac{1}{2014.2016}\right)\)

    \(C=\frac{4}{1.3}.\frac{9}{2.4}.\frac{16}{3.5}........\frac{4060225}{2014.2016}\)

    \(C=\frac{2.2}{1.3}.\frac{3.3}{2.4}.\frac{4.4}{3.5}........\frac{2015.2015}{2014.2016}\)

   \(C=\frac{2.3.4......2015}{1.2.3......2014}.\frac{2.3.4.........2015}{3.4.5.........2016}\)

   \(C=2015.\frac{1}{1008}\)

   \(C=\frac{2015}{1008}\)

Vậy \(C=\frac{2015}{1008}\)