Question

tim x biet

a)2^x+2 -2^x=96

b)x-(50x/100+25x/200)=11^1/₄

c) (x-5).30/100=200x/100+5

Answer 1

a) \(2^{x+2}-2^2=96\)

 <=> \(2^x.2^2-2^x=96\)

 <=> \(2^x\left(4-1\right)=96\)

<=> \(3.2^x=96\)

<=> \(2^x=32\)

<=> \(2^x=2^5\)

<=> x = 5 

Answer 2

b, \(x-\left(\frac{50x}{100}+\frac{25x}{200}\right)=11\frac{1}{4}\)

\(\Rightarrow x-\left(\frac{1x}{2}+\frac{1x}{8}\right)=\frac{45}{4}\)

\(\Rightarrow x-\left(\frac{4x}{8}+\frac{1x}{8}\right)=\frac{45}{4}\)

\(\Rightarrow x-\frac{5x}{8}=\frac{45}{4}\)

\(\Rightarrow\frac{8x}{8}-\frac{5x}{8}=\frac{45}{4}\)

\(\Rightarrow\frac{3x}{8}=\frac{45}{4}\Rightarrow x=\frac{45}{4}\div\frac{3}{8}=30\)

Vậy x = 30