b: A=1/3+1/9+...+1/3^10

=>3A=1+1/3+...+1/3^9

=>A*2=1-1/3^10=(3^10-1)/3^10

=>A=(3^10-1)/(2*3^10)

c: C=3/2+3/8+3/32+3/128+3/512

=>4C=6+3/2+...+3/128

=>3C=6-3/512

=>C=1023/512

d: A=1/2+...+1/256

=>2A=1+1/2+...+1/128

=>A=1-1/256=255/256

b là 255/256

còn c chờ mình

\(\left(\dfrac{-3}{4}\right)^{3x-1}=\dfrac{256}{81}\)

\(\Rightarrow\left(\dfrac{-3}{4}\right)^{3x-1}=\left(\dfrac{4}{3}\right)^4\)

Xem lại đề

\(\left(-\dfrac{3}{4}\right)3x-1=\dfrac{256}{81}\)

\(-\dfrac{9}{4}\cdot x=\dfrac{337}{81}\)

\(x=\dfrac{337}{81}\cdot-\dfrac{4}{9}\)

\(x=-\dfrac{1348}{729}\)

Sửa đề:

(-3/4)³ˣ⁻¹ = 81/256

(-3/4)³ˣ⁻¹ = (-3/4)⁴

3x - 1 = 4

3x = 4 + 1

3x = 5

x = 5/3

a) (1+3x)^4 = 256

=> (1+3x)^4= 4^4

=> 1+3x=4

=> 3x=3

=> x=1

b) \(\frac{3^{15}.29+3^{15}.88}{3^{13}.81}=\frac{3^{15}.\left(29+88\right)}{3^{13}.81}=\frac{3^{15}.117}{3^{13}.81}=\frac{3^2.13}{9}=13\)

\(\left(\frac{-3}{4}\right)^{3x+5}=\left(\frac{81}{256}\right)^{-1}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x+5}=\frac{256}{81}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^{3x+5}=\left(\frac{-3}{4}\right)^{-4}\)

\(\Rightarrow3x+5=-4\)

\(\Rightarrow3x=-9\)

\(\Rightarrow x=-3\)

Vậy x= -3

😅😅😅

a.(2x +1). (2x+1)=1

Mà chỉ có 1.1=1

Vậy 2x + 1=1

               2x=1-1

               2x=0 

Suy ra: x= 0

Hoàng Khánh Thi thiếu nha.

a) (2x+1)² = \(\left(\pm1\right)^2\)

=> 2x + 1 = 1 hoặc 2x + 1 = -1

=> 2x = 0 hoặc 2x = -2

=> x = 0 hoặc x = -1.

anh_hung_lang_la thì làm đi

bọn kia có trả lời câu hỏi không thì bảo

1)=1023/1024

2)=1093/729