C) x-135=315-450

X-135=-135

X=0

D) 346+(210-x)=556

X-210=346-556

X-210=-210

X=0

Lời giải:

a. $145-135(x-2)^2=10$

$135(x-2)^2=145-10=135$

$(x-2)^2=135:135=1=1^2=(-1)^2$
$\Rightarrow x-2=1$ hoặc $x-2=-1$

$\Rightarrow x=3$ hoặc $x=1$

--------------------------

b.

$x\in Ư(36); x\geq 12$

$\Rightarrow x\in\left\{12; 18; 36\right\}$

c.

$x-1=B(9)\Rightarrow x-1\in\left\{0; 9; 18; 27; 36; 45;54;.....\right\}$

$\Rightarrow x\in\left\{1; 10; 19; 28; 37;46; 55;....\right\}$

Mà $25< x< 50$ nên $x\in\left\{28; 37; 46\right\}$

x = 5/6 - 5/7

x = 5/42

x = 2/3 - 13/21

x = 1/21

\(x=\dfrac{5}{6}-\dfrac{5}{7}=\dfrac{5}{42}\)

\(x=\dfrac{2}{3}-\dfrac{13}{21}=\dfrac{1}{21}\)

TL :

\(3\frac{2}{5}\)x 2 x X = \(\frac{3}{5}\)

\(\frac{17}{5}\)x 2 x X = \(\frac{3}{5}\)

\(\frac{34}{5}\)x X = \(\frac{3}{5}\)

X = \(\frac{34}{5}\): \(\frac{3}{5}\)

X = \(\frac{34}{3}\)

=>x-2/3=-1/12

hay x=7/12

\(\dfrac{3}{4}-\left(x-\dfrac{2}{3}\right)=\dfrac{5}{6}\\ \Rightarrow x-\dfrac{2}{3}=\dfrac{3}{4}-\dfrac{5}{6}\\ \Rightarrow x-\dfrac{2}{3}=-\dfrac{1}{12}\\ \Rightarrow x=\dfrac{2}{3}-\dfrac{1}{12}\\ \Rightarrow x=\dfrac{7}{12}\)

\(\left(\dfrac{3}{2}x-\dfrac{1}{5}\right)^2\left(x^2+\dfrac{1}{2}\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}\dfrac{3}{2}x-\dfrac{1}{5}=0\\x^2+\dfrac{1}{2}=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}\dfrac{3}{2}x=\dfrac{1}{5}\\x^2=-\dfrac{1}{2}\left(VLý\right)\end{matrix}\right.\)

\(\Rightarrow x=\dfrac{2}{15}\)

`1/9(x-3)^2-1/25(x+5)^2=0`

`<=>(1/3x-1)^2-(1/5x+1)^2=0`

`<=>(1/3x-1-1/5x-1)(1/3x-1+1/5x+1)=0`

`<=>(2/15x-2). 8/15x=0`

`<=>2/15x-2=0` hoặc `8/15x=0`

`<=>x=15`         hoặc `x=0`

Vậy `S=`{`15;0`}

\(\dfrac{5}{x-3}+\dfrac{4}{x+3}=\dfrac{x-5}{x^2-9}\left(ĐKXĐ:x\ne\pm3\right)\\ \Leftrightarrow\dfrac{5\left(x+3\right)+4\left(x-3\right)}{x^2-9}=\dfrac{x-5}{x^2-9}\\ \Leftrightarrow5x+15+4x-12=x-5\\ \Leftrightarrow5x+4x-x=-5-15+12\\ \Leftrightarrow8x=-8\\ \Leftrightarrow x=-1\left(TM\right)\\ Vậy:S=\left\{-1\right\}\)

\(\frac{4}{7}+x\times2=\frac{5}{3}\)

           \(x\times2=\frac{5}{3}-\frac{4}{7}\)

           \(x\times2=\frac{23}{21}\)

                    \(x=\frac{23}{21}:2\) 

                     \(x=\frac{23}{42}\)

\(\frac{4}{7}+x\times2=\frac{5}{3}\)

          \(x\times2=\frac{5}{3}-\frac{4}{7}\)

           \(x\times2=\frac{23}{21}\)

                   \(x=\frac{23}{21}:2\)

                   \(x=\frac{23}{42}\)

Vậy x = 23/42

Tui cux k bt nữa tui tính rồi mà tinhs mãi k ra 

Bà bt ln chưa chỉ tôi vs