A = 1 +  3  + 3² + 3³ + ... + 3¹⁰⁰

3A = 3 + 3² + 3³ +3⁴+ .... + 3¹⁰¹

3A - A = (3 + 3² + 3⁴ + ... + 3¹⁰¹) - (1 + 3 + 3² + 3³ + ... + 3¹⁰⁰)

2A     = 3 + 3² + 3⁴ + ... + 3¹⁰¹ - 1 - 3 - 3² - 3³ - ... - 3¹⁰⁰

2A = (3 - 3) + (3² - 3²) + ... + (3¹⁰⁰ - 3¹⁰⁰) + (3¹⁰¹ - 1)

2A = 3¹⁰¹ - 1

A = \(\dfrac{3^{101}-1}{2}\)

Ta có:

\(\begin{array}{l}\frac{{24}}{{108}} = \frac{{24:12}}{{108:12}} = \frac{2}{9};\\\frac{{80}}{{32}} = \frac{{80:16}}{{32:16}} = \frac{5}{2}\end{array}\)

\(\dfrac{24}{32}=\dfrac{24:8}{32:8}=\dfrac{3}{4}\)

\(\dfrac{45}{6}=\dfrac{45:3}{6:3}=\dfrac{15}{2}\)

\(\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

\(\dfrac{27}{63}=\dfrac{27:9}{63:9}=\dfrac{3}{7}\)

\(\dfrac{24}{32}=\dfrac{24:8}{32:8}=\dfrac{3}{4}\)

\(\dfrac{75}{100}=\dfrac{75:25}{100:25}=\dfrac{3}{4}\)

\(\dfrac{45}{60}=\dfrac{45:15}{60:15}=\dfrac{3}{4}\)

\(\dfrac{27}{63}=\dfrac{27:9}{63:9}=\dfrac{3}{7}\)

\(\frac{24}{32}=\frac{24:8}{32:8}=\frac34\)

\(\frac{14}{35}=\frac{14:7}{35:7}=\frac25\)

\(\frac{30}{25}=\frac{30:5}{25:5}=\frac65\)

\(\frac{63}{36}=\frac{63:9}{36:9}=\frac74\)

18/27=2/3

24/32=3/4

15/25=3/5

2/3 , 3/4 , 3/5

a) \(\dfrac{4}{5}+\dfrac{3}{15}=\dfrac{4}{5}+\dfrac{1}{5}=\dfrac{5}{5}=1\)

b) \(\dfrac{2}{3}+\dfrac{32}{24}=\dfrac{2}{3}+\dfrac{4}{3}=\dfrac{6}{3}=2\)

c) \(\dfrac{5}{6}+\dfrac{15}{18}=\dfrac{5}{6}+\dfrac{5}{6}=\dfrac{10}{6}=\dfrac{5}{3}\).

1112 phần 2339 nha bn

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