Question

Tìm x, biết:

a)\(\frac{2^{2x-3}}{4^{10}}=8^3.16^5\)

b)7.2 ^x =2 ⁹+5.2 ⁸

Answer 1

a, Tự chép đề bài :v

=> 2^2x-3 = ( 8³. 16⁵ ) : 4¹⁰

2^2x-3 = ( 2⁹. 2²⁰ ) : 2²⁰

2^2x-3 = 2²⁹ : 2²⁰

2^2x-3 = 2⁹

=> 2x - 3 = 9

2x = 9 + 3

2x = 12

x = 6 

Vậy....

b, 7. 2^x = 2⁹ + 5. 2⁸

7. 2^x = 1792

2^x = 1792 : 7

2^x = 256

2^x = 2⁸

=> x = 8 

Vậy ....

Answer 2

a  \(\frac{2^{2x-3}}{4^{10}}=8^3.16^5\)

\(\Leftrightarrow\frac{2^{2x-3}}{4^{10}}=2^{29}\)

\(\Leftrightarrow2^{2x-3}=2^{29}.4^{10}\)

\(\Leftrightarrow2^{2x-3}=2^{49}\)

\(\Leftrightarrow2x-3=49\)

\(\Leftrightarrow x=26\)

b  \(7.2^x=2^9+5.2^8\)

\(\Leftrightarrow7.2^x=2^8.(2+5)\)

\(\Leftrightarrow7.2^x=7.2^8\)

\(\Leftrightarrow x=7\)