Question

[Đoàn Ngọc Yến Nhi]

Tìm x biết : a)\(1-\dfrac{1}{2}.\left(\dfrac{3}{2}-2.x\right)=4.x-\dfrac{1}{4}\) b):\(x^{10}=1024\) c) 3^x = 81

Answer 1

[Trần Nguyễn Bảo Quyên]

\(a.\)

\(1-\dfrac{1}{2}\left(\dfrac{3}{2}-2x\right)=4x-\dfrac{1}{4}\)

\(\Rightarrow1-\dfrac{3}{4}+x=4x-\dfrac{1}{4}\)

\(\Rightarrow1-\dfrac{3}{4}+\dfrac{1}{4}=4x-x\)

\(\Rightarrow3x=\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{6}\)

\(b.\)

\(x^{10}=1024\)

\(\Rightarrow x^{10}=2^{10}\)

\(\Rightarrow x=2\)

\(c.\)

\(3^x=81\)

\(\Rightarrow3^x=3^4\)

\(\Rightarrow x=4\)