đăng từng bài thui bạn êi ~.~
\(a)\)\(4x^3+12=120\)
\(\Leftrightarrow\)\(4x^3=108\)
\(\Leftrightarrow\)\(x^3=27\)
\(\Leftrightarrow\)\(x^3=3^3\)
\(\Leftrightarrow\)\(x=3\)
Vậy \(x=3\)
\(b)\) \(\left(4x-1\right)^2=25.9\)
\(\Leftrightarrow\)\(\left(4x-1\right)^2=5^2.3^2\)
\(\Leftrightarrow\)\(\left(4x-1\right)^2=\left(5.3\right)^2\)
\(\Leftrightarrow\)\(\left(4x-1\right)^2=15^2\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}4x-1=15\\4x-1=-15\end{cases}\Leftrightarrow\orbr{\begin{cases}4x=16\\4x=-14\end{cases}}}\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x=\frac{16}{4}\\x=\frac{-14}{4}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=4\\x=\frac{-7}{2}\end{cases}}}\)
Vậy \(x=4\) hoặc \(x=\frac{-7}{2}\)
Chúc bạn học tốt ~
\(\left(2x-15\right)^{15}=\left(2x-15\right)^3\)
\(\Leftrightarrow\)\(\left(2x-15\right)^{15}-\left(2x-15\right)^3=0\)
\(\Leftrightarrow\)\(\left(2x-15\right)^3[\left(2x-15\right)^{12}-1]=0\)
\(\Leftrightarrow\)\(\left(2x-15\right)^3=0\)
Hoặc \(\left(2x-15\right)^{12}-1=0\)
\(\Leftrightarrow\)\(2x-15=0\)
Hoặc \(\left(2x-15\right)^{12}=1\)
\(\Leftrightarrow\)\(2x=15\)
Hoặc \(\orbr{\begin{cases}2x-15=1\\2x-15=-1\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=16\\2x=14\end{cases}}}\)
\(\Leftrightarrow\)\(x=\frac{15}{2}=7,5\)
Hoặc \(\orbr{\begin{cases}x=\frac{16}{2}\\x=\frac{14}{2}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=8\\x=7\end{cases}}}\)
Vậy \(x=7\)\(;\)\(x=7,5\) hoặc \(x=8\)
Chúc bạn học tốt ~
