Question

Câu 1 : Tìm x

a, 2^x + 2^{x + 2} = 144

b , ( 2x + 1 ) ³ = 125

Answer 1

câu b nhé

vì 5^3 =25

suy ra 2x+1=5

2x=5-1

2x=4

x=4/2

x=2

Answer 2

a/ \(2^x+2^{x+2}=144\)

\(\Rightarrow2^x+2^x.2^2=144\)

\(\Rightarrow2^x\left(2^2+1\right)=144\)

\(\Rightarrow2^x=\dfrac{144}{5}\)

\(\Rightarrow2^x=28.8\)

\(\Rightarrow x=4,847996907\) (ở câu này mk nghĩ đề sai)

b/ \(\left(2x+1\right)^3=125\)

\(\Rightarrow\left(2x+1\right)^3=5^3\)

\(\Rightarrow2x+1=5\)

\(\Rightarrow x=\dfrac{5-1}{2}=2\)

Vậy \(x=2\)