Bantuin jawab, ka! Beserta pembahasannya, ya... no 29 dan 31.

29.)
Untuk soal ini kita bisa gunakan rumus cepat
[tex] \frac{1}{1 \times 2 \times 3} + \frac{1}{2 \times 3 \times 4} + \frac{1}{3 \times 4 \times 5} + ... + \frac{1}{(n)(n+1)(n+2)} = \frac{n(n+3)}{4(n+1)(n+2)} [/tex]

Sehingga
[tex] \frac{1}{1 \times 2 \times 3} + \frac{1}{2 \times 3 \times 4} + \frac{1}{3 \times 4 \times 5} + ... + \frac{1}{1996 \times 1997 \times 1998} = \frac{1996 \times 1999}{4 \times 1997 \times 1998} [/tex]
= [tex] \frac{997501}{3990006} [/tex]
≈ 0,25

31.)
[tex] \frac{1}{\sqrt{1} + \sqrt{2}} + \frac{1}{\sqrt{2} + \sqrt{3}} + \frac{1}{\sqrt{3} + \sqrt{4}} + ... + \frac{1}{\sqrt{99} + \sqrt{100}} [/tex]
= (-√1 + √2) + (-√2 + √3) + (-√3 + √4) + ... + (-√99 + √100)
= - √1 + 100
= -1 + 10
= 9