b) \(\left(x-3\right)^2=0,25\)
\(\Rightarrow\left(x-3\right)^2=\left(\pm0,5\right)^2\)
\(\Rightarrow x-3=\pm0,5.\)
\(\Rightarrow\left[{}\begin{matrix}x-3=0,5\\x-3=-0,5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0,5+3\\x=\left(-0,5\right)+3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3,5\\x=2,5\end{matrix}\right.\)
Vậy \(x\in\left\{3,5;2,5\right\}.\)
c) \(\left(2x-1,5\right)^3=\left(-0,27\right)\) (câu này sai đề rồi nhé).
d) \(3.2x+\left(-1,2\right).x+2,7=\left(-4,9\right)\)
\(\Rightarrow3.2x+\left(-1,2\right).x=\left(-4,9\right)-2,7\)
\(\Rightarrow3.2x+\left(-1,2\right).x=-7,6\)
\(\Rightarrow6.x+\left(-1,2\right).x=-7,6\)
\(\Rightarrow\left[6+\left(-1,2\right)\right].x=-7,6\)
\(\Rightarrow4,8.x=-7,6\)
\(\Rightarrow x=\left(-7,6\right):4,8\)
\(\Rightarrow x=-\frac{19}{12}\)
Vậy \(x=-\frac{19}{12}.\)
Chúc bạn học tốt!
b) (x-3)\(^2\) = 0,25
(x-3)\(^2\) = (0,5)\(^2\)
x-3 = 0,5
x = 0,5 + 3
x = 0,8