Question 9
Find the value of
$$\frac 2{4\times 5}+\frac 2{5\times 6}+\frac 2{6\times 7}+\cdots+\frac 2{47\times 48}+\frac 2{48\times 49}+\frac 2{49\times 50}.$$
$$\frac 2{4\times 5}+\frac 2{5\times 6}+\frac 2{6\times 7}+\cdots+\frac 2{47\times 48}+\frac 2{48\times 49}+\frac 2{49\times 50}.$$