Câu hỏi của Nguyễn Minh Dương

Question

Tìm x: 35 - [ ( 2x - 3)2 : 7 ] = 28

HELP ME!

Nguyễn Đức Trí · Accepted Answer

$35-\left[\left(2x-3\right)^2:7\right]=28$

$\Rightarrow\left[\left(2x-3\right)^2:7\right]=35-28$

$\Rightarrow\left(2x-3\right)^2:7=7$

$\Rightarrow\left(2x-3\right)^2=1$

$\Rightarrow2x-3=\pm1$

$\Rightarrow x=2$ hay $x=1$Câu trả lời: $35-\left[\left(2x-3\right)^2:7\right]=28$

$\Rightarrow\left[\left(2x-3\right)^2:7\right]=35-28$

$\Rightarrow\left(2x-3\right)^2:7=7$

$\Rightarrow\left(2x-3\right)^2=1$

$\Rightarrow2x-3=\pm1$

$\Rightarrow x=2$ hay $x=1$

Nguyễn Thị Thương Hoài · Answer

35 - [(2$x$ - 3)2:7 ] = 28

(2$x-3$)2 : 7 = 35 - 28

(2$x$ - 3)2 : 7 = 7

(2$x$ - 3)2      = 7 $\times$ 7

(2$x-3$)2 = 72

$\left[{}\begin{matrix}2x-3=-7\2x-3=7\end{matrix}\right.$

$\left[{}\begin{matrix}2x=-7+3\2x=7+3\end{matrix}\right.$

$\left[{}\begin{matrix}2x=-4\2x=10\end{matrix}\right.$

$\left[{}\begin{matrix}x=-2\x=5\end{matrix}\right.$

Vậy $x\in$ {-2; 5}

Câu trả lời: 35 - [(2$x$ - 3)2:7 ] = 28