\(a.\left(x+5\right)^3=-64\Leftrightarrow x+5=-4\Leftrightarrow x=-9\\ b.\left(2x-3\right)^2=9\Leftrightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)
( Nhớ kết luận! )
a.
\(\left(x+5\right)^3=\left(-4\right)^3\)
\(\Leftrightarrow x+5=-4\)
\(\Leftrightarrow x=-9\)
b.
\(\left(2x-3\right)^2=3^2\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)
a)(x+5)3=−64
\(\left(x+5\right)^3=\left(-4\right)^3\)
x+5=−4
x=−4−5=-9
Vậy x=−9
b)(2x−3)3=8(9 không được)
\(\left(2x-3\right)^3=2^3\)
2x−3=2
2x=5
x\(=\dfrac{5}{2}\)
P/s Nhớ tick cho mình nha. Thanks bạn