Câu hỏi của Hương Giang

Question

tìm x:

a) (22)x = 25

b) (3x)2 = 81

c) 8x +1 = 23003

d) 8x+1 = 41002

Mặc Chinh Vũ · Accepted Answer

$a)\left(2^2\right)^x=2^5$

$\Leftrightarrow2^{2x}=2^5$

$\Leftrightarrow2x=5$

$\Leftrightarrow x=2,5$

$b)\left(3^x\right)^2=81$

$\Leftrightarrow3^{2x}=3^4$

$\Leftrightarrow2x=4$

$\Leftrightarrow x=2$

$c)8^{x+1}=2^{3003}$

$\Leftrightarrow\left(2^3\right)^{x+1}=2^{3003}$

$\Leftrightarrow2^{3\left(x+1\right)}=2^{3003}$

$\Leftrightarrow3\left(x+1\right)=3003$

$\Leftrightarrow x+1=1001$

$\Leftrightarrow x=1000$

$d)8^{x+1}=4^{1002}$

$\Leftrightarrow\left(2^3\right)^{x+1}=\left(2^2\right)^{1002}$

$\Leftrightarrow2^{3\left(x+1\right)}=2^{2004}$

$\Leftrightarrow3\left(x+1\right)=2004$

$\Leftrightarrow x+1=668$

$\Leftrightarrow x=667$Câu trả lời: $a)\left(2^2\right)^x=2^5$