Ăn đầu buồi

Ta có n.(n+1) =2.300

n.(n+1)=600

n.(n+1)=2³.3.5²

n.(n+1)=24.25

vậy n=24

b) 200 x 4 = .800.....              300 x 2 = ..600....

200 x 2 = .400.....             300 x 3 = ...900...

400 x 2 = ...800...             500 x 1 = ..500....

100 x 4 = ..400....             100 x 3 = .300.....

800

400

800

400

600

900

500

300

ai giúp mình với

=>1/4x+300=800

=>1/4x=500

hay x=2000

\(\dfrac{1}{4}\left(\dfrac{1}{4}x+300\right)=200\)

\(\Leftrightarrow\dfrac{1}{4}x+300=800\)

\(\Leftrightarrow\dfrac{1}{4}x=500\)

\(\Leftrightarrow x=2000\)

\(\left(1+\frac{1}{2}\right).\left(1+\frac{1}{3}\right).\left(1+\frac{1}{4}\right)...\left(1+\frac{1}{300}\right)\)

\(=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}...\frac{301}{300}\)

\(=\frac{301}{2}\)

\(\left(1+\frac{1}{2}\right)\cdot\left(1+\frac{1}{3}\right)\cdot\left(1+\frac{1}{4}\right)\cdot...\cdot\left(1+\frac{1}{300}\right)\)

\(=\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot...\cdot\frac{301}{300}\)

\(=\frac{3\cdot4\cdot5\cdot...\cdot301}{2\cdot3\cdot4\cdot...\cdot300}=\frac{301}{2}\)

P/s : bài này lớp 6 nhé bn :)

1/3^400=1/81^100

1/4^300=1/64^100

=> 1/3^400<1/4^300

1/3>1/4

mà 400>300

=> 1/3^400>1/4^300

mik làm lại nka, ban đầu có 1 chút sai lầm

mik cx làm giống b ở trên