`Answer:`

b. \(-\left(2a-b-2c\right)+\left(-a-b\right)-\left(-2+2b-c\right)+b-1\)

\(=-2a+b+2c+-a-b+2-2b+c+b-1\)

\(=-2a-a+b-b-2b+b+2c+c+2-1\)

\(=-3a-2b+3c+1\)

c. \(\left(-46-c\right)-\left(-2+b-3\right)+\left(2c+b-a+4\right)\)

\(=-46-c+2-b+3+2c+b-a+4\)

\(=-a-b+b-c+2c-46+3+4+2\)

\(=-a+c-37\)

a) \(A=\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+......+\frac{1}{2017.2022}\)

\(5A=5.\left(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+.....+\frac{1}{2017.2022}\right)\)

\(5A=\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+......+\frac{5}{2017.2022}\)

\(5A=1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+........+\frac{1}{2017}-\frac{1}{2022}\)

\(5A=1-\frac{1}{2022}\)

\(5A=\frac{2022}{2022}-\frac{1}{2022}\)

\(5A=\frac{2021}{2022}\)

\(A=\frac{2021}{2022}\div5\)

\(A=\frac{20201}{10110}\)

TL: 

\(\frac{5}{6}=\frac{1}{2}+\frac{1}{3}\) 

@@@@@@@@@@ 

HT

thang

thang

`Answer:`

\(A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\)

\(\Rightarrow2A=2\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\right)\)

\(\Rightarrow2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{98}}+\frac{1}{2^{99}}\)

\(\Rightarrow2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{98}}+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\right)\)

\(\Rightarrow A=1-\frac{1}{2^{100}}\)

\(B=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{13}{60}\)

\(\Rightarrow B=\frac{20}{60}+\frac{15}{60}+\frac{12}{60}+\frac{13}{60}\)

\(\Rightarrow B=1\)

Mà \(1-\frac{1}{2^{100}}< 1\)

`=>A<B`

$A=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}$

$\Rightarrow 2A=2\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\right)$

$\Rightarrow 2A=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{98}}+\frac{1}{2^{99}}$

$\Rightarrow 2A-A=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{98}}+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{99}}+\frac{1}{2^{100}}\right)$

$\Rightarrow A=1-\frac{1}{2^{100}}$

$B=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{13}{60}$

$\Rightarrow B=\frac{20}{60}+\frac{15}{60}+\frac{12}{60}+\frac{13}{60}$

$\Rightarrow B=$

Mà $1-\frac{1}{2^{100}}<1$

$\Rightarrow A<B$

Chiều rộng mảnh đất đó là:

\(100\text{x}\frac{4}{5}=80\left(m\right)\)

Diện tích mảnh đất đó là:
\(100\text{x}80=8000\left(m^2\right)\)

Diện tích trồng chuối là:

\(8000\text{x}60\%=4800\left(m^2\right)\)

Đáp số: \(4800m^2\)