Question

tính C= -1/1x2- 1/2x3- 1/3x4- ...-1/42x43- 1/43x44

Answer 1

\(C=-1+\frac{1}{2}-\frac{1}{2}+\frac{1}{3}-\frac{1}{3}+\frac{1}{4}-....-\frac{1}{42}+\frac{1}{43}-\frac{1}{43}+\frac{1}{44}\)

\(C=-1+\frac{1}{44}\)

\(C=-\frac{43}{44}\)

Answer 2

C= \(-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...\frac{1}{43.44}\right)=-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{43}-\frac{1}{44}\right)\)

 =\(-\left(1-\frac{1}{44}\right)=-\frac{43}{44}\)