b) 3.[5^2x+1 - (5²)^x] = 3.100

3( 5^2x+1-5^2x) = 3.100

-> 5^2x+1-5^2x = 100

mà 5³-5²= 100

-> 5^2x+1-5^2x = 5³-5²

^{Vậy x = 1}

c) (4²)^x : 4^x = 4²

<=>4^2x-x =4²

<=> 4^x = 4²

-> x=2

d) 2^x( 0,5 +4) = 72

2^x. 4,5 = 72

2^x = 72:4,5 = 16

2^x = 2⁴ = 16

-> x= 4

\(\Leftrightarrow3^x\cdot\dfrac{1}{3}+5\cdot3^x\cdot\dfrac{1}{3}=72\)

\(\Leftrightarrow3^x\cdot2=72\)

\(\Leftrightarrow3^x=36\)

hay \(x\in\varnothing\)

\(9^{x+1}-5.3^{2x}=324\)

\(\Rightarrow9^x.9-5.9^x=324\)

\(\Rightarrow9^x\left(9-5\right)=324\)

\(\Rightarrow9^x.4=324\)

\(\Rightarrow9^x=81\)

\(\Rightarrow9^x=9^2\)

vậy x=2

\(\Rightarrow x=2\)

\(9^{x+1}-5.3^{2x}=324\)

\(9^x.9-5.9^x=324\)

\(9^x.\left(9-5\right)=324\)

\(9^x.4=324\)

\(9^x=81=9^2\)

\(\Rightarrow x=2\)

x=2 bạn nhe!

\(9^{x+1}+5.3^{2x}=324\)

\(9^x.9+5.\left(3^2\right)^x=324\)

\(9^x.9+5.9^x=324\)

\(9^x.\left(5+9\right)=324\)

\(9^x.14=324\)

\(9^x=\frac{324}{14}\)

\(\Rightarrow x\in\varnothing\)

a) 5^{x + 1} - 2.5^x = 75

<=> 5^x.5 - 2.5^x = 75

<=> 5^x.3 = 75

<=> 5^x = 25

<=> 5^x = 5²

<=> x = 2

Vậy x = 2

b) 9^{x + 1} -  5.3^2x = 324

<=> (3²)^{x + 1} - 5.3^2x = 324

<=> 3^{2x + 2} - 5.3^2x = 324

<=> 3^2x.3² - 5.3^2x = 324

<=> 3^2x . 4 = 324

<=> 3^2x = 81

<=> 3^2x = 3⁴

<=> 2x = 4

<=> x = 2

Vậy x = 2

UIUYI