Question

Answer 1

C=\(\dfrac{6}{1.3}+\dfrac{6}{3.5}+\dfrac{6}{5.7}+\dfrac{6}{7.9}\)

C=\(3.\left(\dfrac{2}{1.3}+\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}\right)\)

C=\(3.\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{7}-\dfrac{1}{9}\right)\)

C=\(3.\left(1-\dfrac{1}{9}\right)\)

C=\(3.\dfrac{8}{9}\)=\(\dfrac{8}{3}\)

Answer 2

D=\(\dfrac{3}{4.9}+\dfrac{3}{9.14}+\dfrac{3}{14.19}+\dfrac{3}{19.24}\)

D=\(\dfrac{3}{5}.\left(\dfrac{5}{4.9}+\dfrac{5}{9.14}+\dfrac{5}{14.19}+\dfrac{5}{19.24}\right)\)

D=\(\dfrac{3}{5}.\left(\dfrac{1}{4}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{14}+...+\dfrac{1}{19}-\dfrac{1}{24}\right)\)

D=\(\dfrac{3}{5}.\left(\dfrac{1}{4}-\dfrac{1}{24}\right)\)D=\(\dfrac{3}{5}.\dfrac{5}{24}=\dfrac{1}{8}\)