\(460+85\times4=\left(x+200\right)\times4\)

\(\left(x+200\right)\times4=460+340\)

\(\left(x+200\right)\times4=800\)

\(x+200=800:4\)

\(x+200=200\)

\(x=200-200\)

\(x=0\)

~~~

\(\left(x-7\right)\left(2x-8\right)=0\)

\(+, TH1: x - 7 = 0\)

\(x=0+7\)

\(x=7\)

\(+, TH2 : 2x - 8 = 0 \)

\(2x=0+8\)

\(2x=8\)

\(x=8:2\)

\(x=4\)

~~~

\(x-280:35=5\times54\)

\(x-8=270\)

\(x=270+8\)

\(x=278\)

~~~

\(324+16\times\left(2x+3\right)=404\)

\(16\times\left(2x+3\right)=404-324\)

\(16\times\left(2x+3\right)=80\)

\(2x+3=80:16\)

\(2x+3=5\)

\(2x=5-3\)

\(2x=2\)

\(x=2:2\)

\(x=1\)

#\(Toru\)

`460 + 85 xx 4 = ( x + 200) xx 4`

`460 + 340 = (x+200)xx4`

` 800= (x+200)xx4`

`x+200=800:4`

`x+200=200`

`x=200-200`

`x=0`

__

`(x-7)(2x-8)=0`

`@ TH1`

`x-7=0`

`x=0+7`

`x=7`

`@ TH2`

`2x-8=0`

`2x=0+8`

`2x=8`

`x=8:2`

`x=4`

__

`x -280 : 35=5xx54`

`x -280 : 35=270`

`x-8=270`

`x=270+8`

`x=278`

__

`324 + 16xx(2x+3)=404`

`16xx(2x+3)=404 -324`

`16xx(2x+3)=80`

`2x+3=80:16`

`2x+3=5`

`2x=5-3`

`2x=2`

`x=2:2`

`x=1`

`Answer:`

Vì đề bài khá khó nhìn nên mình làm thành hai bài nhé. Đề nào đúng thì bạn tham khảo.

`x : (9 1/2 - 3/2 ) = 0,4 + 2/9 - 2/11 . 1/6 + 8/9 - 8/11`

`=> x : ( 19/2 - 3/2 ) = 28/45 - 1/33 + 8/9 - 8/11`

`=> x : 8 = 293/495 + 8/9 - 8/11`

`=> x : 8 = 733/495 - 8/11`

`=> x : 8 = 373/495`

`=> x = 373/495 .8`

`=> x = 2984/495`

`x : ( 9 1/2 - 3/2 ) = (0,4 + 2/9 - 2/11 )/(1,6 + 8/9 - 8/11 )`

`=> x : (19/2 - 3/2 ) = (2 . (1/5 + 1/9 - 1/11))/(8.(1/5 + 1/9 - 1/11))`

`=> x : 8 = 2/8`

`=> x = 2/8 .8`

`=> x = 2`

\(x:\left(9+\frac{1}{2}-\frac{3}{2}\right)=\frac{2\left(\frac{1}{5}+\frac{1}{9}+\frac{1}{11}\right)}{8\left(\frac{1}{5}+\frac{1}{9}+\frac{1}{11}\right)}\)

\(x:8=\frac{1}{4}\)

x=2

\(\left(\dfrac{3x-5}{9}\right)^{2018}>=0\forall x\)

\(\left(\dfrac{3y+0,4}{3}\right)^{2020}>=0\forall y\)

Do đó: \(\left(\dfrac{3x-5}{9}\right)^{2018}+\left(\dfrac{3y+0,4}{3}\right)^{2020}>=0\forall x,y\)

Dấu '=' xảy ra khi \(\left\{{}\begin{matrix}\dfrac{3x-5}{9}=0\\\dfrac{3y+0,4}{3}=0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}3x-5=0\\3y+0,4=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{5}{3}\\y=-\dfrac{0.4}{3}=-\dfrac{2}{15}\end{matrix}\right.\)

B,

Tính trong ngoặc trước:(1+2) =3

Ta có: 6 : 2 : 3 = 3 : 3 = 1

=> Đáp án đúng là B

\(6:2\left(1+2\right)=6:2.3=9\)

\(\Rightarrow B\) \(đúng\)

a) \(x=-\dfrac{3}{5}\times\dfrac{9}{7}=-\dfrac{27}{35}\)

b) \(x\left(0,4-\dfrac{1}{5}\right)=\dfrac{3}{4}\)

\(x=\dfrac{3}{4}:\dfrac{1}{5}=\dfrac{15}{4}\)

a, \(x=-3,5.\dfrac{9}{7}=-\dfrac{9}{2}\)

b, \(\dfrac{2}{5}x-\dfrac{1}{5}x=\dfrac{3}{4}\Leftrightarrow\dfrac{1}{5}x=\dfrac{3}{4}\Leftrightarrow x=\dfrac{3}{4}:\dfrac{1}{5}=\dfrac{15}{4}\)

x=\(\dfrac{9}{7}x-3.5\)

x=\(\dfrac{-9}{5}\)

5/3x = 9/40+0,4

5/3x = 5/8

x = 5/8:5/3

x = 3/8

\(\frac{5}{3}x-0,4=\frac{9}{40}\)

\(\Rightarrow\frac{5}{3}x=\frac{9}{40}+0,4\)

\(\Rightarrow\frac{5}{3}x=\frac{5}{8}\)

\(\Rightarrow x=\frac{5}{8}:\frac{5}{3}\)

\(\Rightarrow x=\frac{3}{8}\)

vậy x=\(\frac{3}{8}\)

x x 9 - 23 = 40