B=1.44​+4.74​+7.104​+....+94.974​+97.1004​

\(B = 4 \left(\right. \frac{1}{1.4} + \frac{1}{4.7} + \frac{1}{7.10} + . . . . + \frac{1}{94.97} + \frac{1}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. \frac{3}{1.4} + \frac{3}{4.7} + \frac{3}{7.10} + . . . . + \frac{3}{94.97} + \frac{3}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{4} + \frac{1}{4} - \frac{1}{7} + \frac{1}{7} - \frac{1}{10} + . . . . + \frac{1}{94} - \frac{1}{97} + \frac{1}{97} - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} . \frac{99}{100}\)

\(B = \frac{33}{25}\).

Vậy \(B = \frac{33}{25}\).

B=1.44​+4.74​+7.104​+....+94.974​+97.1004​

\(B = 4 \left(\right. \frac{1}{1.4} + \frac{1}{4.7} + \frac{1}{7.10} + . . . . + \frac{1}{94.97} + \frac{1}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. \frac{3}{1.4} + \frac{3}{4.7} + \frac{3}{7.10} + . . . . + \frac{3}{94.97} + \frac{3}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{4} + \frac{1}{4} - \frac{1}{7} + \frac{1}{7} - \frac{1}{10} + . . . . + \frac{1}{94} - \frac{1}{97} + \frac{1}{97} - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} . \frac{99}{100}\)

\(B = \frac{33}{25}\).

Vậy \(B = \frac{33}{25}\).

B=1.44​+4.74​+7.104​+....+94.974​+97.1004​

\(B = 4 \left(\right. \frac{1}{1.4} + \frac{1}{4.7} + \frac{1}{7.10} + . . . . + \frac{1}{94.97} + \frac{1}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. \frac{3}{1.4} + \frac{3}{4.7} + \frac{3}{7.10} + . . . . + \frac{3}{94.97} + \frac{3}{97.100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{4} + \frac{1}{4} - \frac{1}{7} + \frac{1}{7} - \frac{1}{10} + . . . . + \frac{1}{94} - \frac{1}{97} + \frac{1}{97} - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} \left(\right. 1 - \frac{1}{100} \left.\right)\)

\(B = \frac{4}{3} . \frac{99}{100}\)

\(B = \frac{33}{25}\).

Vậy \(B = \frac{33}{25}\).

A=1.21​+3.41​+5.61​+...+49.501​

\(A = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(A = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

A=1.21​+3.41​+5.61​+...+49.501​

\(A = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(A = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

A=1.21​+3.41​+5.61​+...+49.501​

\(A = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(A = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

A=1.21​+3.41​+5.61​+...+49.501​

\(A = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(A = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

A=1.21​+3.41​+5.61​+...+49.501​

\(A = \left(\right. 1 + \frac{1}{3} + \frac{1}{5} + . . . + \frac{1}{49} \left.\right) - \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - 2 \left(\right. \frac{1}{2} + \frac{1}{4} + . . . + \frac{1}{50} \left.\right)\)

\(A = \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + \frac{1}{4} + \frac{1}{5} + \frac{1}{6} + . . . + \frac{1}{49} + \frac{1}{50} \left.\right) - \left(\right. 1 + \frac{1}{2} + \frac{1}{3} + . . . + \frac{1}{25} \left.\right)\)

\(A = \frac{1}{26} + \frac{1}{27} + . . . + \frac{1}{49} + \frac{1}{50} < \frac{1}{26} + \frac{1}{26} + \frac{1}{26} + . . . + \frac{1}{26} = \frac{25}{26} < 1.\)

Chiều dài đám đất là:

60x4/3=80(m)

Diện tích đám đất là:

60x80=4800m2

Diện tính chồng cây là

4800x7/1=2800

Diện tích còn lại là

4800-2800=200

Diện tích ao cá là

2000x30%=600m2

a,(-5/9+-4/9)+(8/15+7/15)+-2/11=-9/9+15/15+2/11=-1+1+-2/11=0+-2/11=-2/11

b,(7/2x5/6)+(7/6x7/2)=7/2x2=7