Question

tính theo cách thuận tiện:

1:(2*3) + 1:(3*4) + 1:(4*5) + 1:(5*6) + 1:(6*7)

Answer 1

1:(2x3) + 1:(3x4) + 1:(4x5) + 1:(5x6) + 1:(6x7)

= \(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}+\frac{1}{6x7}\)

= \(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\)

= \(\frac{1}{2}-\frac{1}{7}\)

= \(\frac{5}{14}\)

cho mình 1 đ-ú-n-g nha bạn