Computing a sum of fractions using sigma notation

322 Views Asked by At

Evaluate the following using sigma notation

$$\frac34 + \frac65 + \frac96 + \frac{12}{7} + \frac{15}{8}$$

For the denominator I get $\sum_{i=4}^8 i$ but how about the numerator?

1

There are 1 best solutions below

3
On

What about

$$\sum_{i=4}^8 \frac{3(i-3)}{i}=3\sum_{i=4}^81-9\sum_{i=4}^8\frac1i$$