\(\dfrac{3}{5}-\dfrac{20}{9}:\dfrac{5}{18}+\dfrac{2}{4}\)

\(=\dfrac{3}{5}-\dfrac{20}{9}\times\dfrac{18}{5}+\dfrac{1}{2}\)

\(=\dfrac{3}{5}-\dfrac{360}{45}+\dfrac{1}{2}\)

\(=\dfrac{3}{5}-8+\dfrac{1}{2}\)

\(=-\dfrac{37}{5}+\dfrac{1}{2}\)

\(=-\dfrac{69}{10}\)

\(\dfrac{3}{5}-\dfrac{20}{9}:\dfrac{5}{18}+2,4\)

\(=\dfrac{3}{5}-8+\dfrac{7}{5}\)

\(=\left(\dfrac{3}{5}+\dfrac{7}{5}\right)-8\)

\(=2-8\)

\(=-6\)

\(a,\Leftrightarrow\left(9x^2-18x+9\right)+\left(y^2-6y+9\right)+\left(2z^2+4z+2\right)=0\\ \Leftrightarrow9\left(x-1\right)^2+\left(y-3\right)^2+2\left(z+1\right)^2=0\\ \Leftrightarrow\left\{{}\begin{matrix}x=1\\y=3\\z=-1\end{matrix}\right.\)

\(b,\Leftrightarrow\left(4x^2+8xy+4y^2\right)+\left(x^2-2x+1\right)+\left(y^2+2y+1\right)=0\\ \Leftrightarrow4\left(x+y\right)^2+\left(x-1\right)^2+\left(y+1\right)^2=0\\ \Leftrightarrow\left\{{}\begin{matrix}x=-y\\x=1\\y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-1\end{matrix}\right.\)

\(c,\Leftrightarrow\left(4x^2+4xy+y^2\right)+\left(x^2-2x+1\right)+\left(y^2+4y+4\right)=0\\ \Leftrightarrow\left(2x+y\right)^2+\left(x-1\right)^2+\left(y+2\right)^2=0\\ \Leftrightarrow\left\{{}\begin{matrix}2x=-y\\x=1\\y=-2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-2\end{matrix}\right.\)

e: Ta có: 

Dấu '=' xảy ra khi x=3 và y=-2

Cho mk xin yêu cầu của bài được ko vậy ???

a. 2x²-5x+1=0

△= b² - 4ac = (-5)² - 4*2*1 = 17 ⇒√△ = √17

\(\Rightarrow x_1=\frac{5+\sqrt{17}}{4};x_2=\frac{5-\sqrt{17}}{4}\)

Vậy .... S={\(\frac{5\pm\sqrt{17}}{4}\)}

b. 4x² +4x+1=0

⇔(2x+1)² = 0 ⇔ x=\(\frac{-1}{2}\)

c. -3x² +2x+8=0

△' = b'² - ac = 1² - (-3)*8 = 25 ⇒√△ = 5

\(\Rightarrow x_1=\frac{-1+5}{-3}=-\frac{4}{3};x_2=\frac{-1-5}{-3}=2\)

Vậy... S={-\(\frac{4}{3}\);2}

d. 5x2 6x1=0 (thiếu dấu nên mk chưa giải được)

e. -3x²+ 14x - 8=0

△' = b'² - ac = 7² - (-3)*(-8) = 25 ⇒ √△ = 5

⇒\(x_1=\frac{-7+5}{-3}=\frac{2}{3};x_2=\frac{-7-5}{-3}=4\)

Vậy .... S={\(\frac{2}{3};4\)}

g. -7x² +4x-3=0

△' = b'² - ac = 2² - (-7)*(-3) = -17<0

Vậy pt vô nghiệm , S=∅

6 x 1 = 6 

5 x 2 = 10

98 x 2 = 196

6 x 1 = 6

5 x 2 = 10

98 x 2 = 196

Hok tốt!!

\(1\frac{1}{5}x1\frac{1}{6}x...x1\frac{1}{2014}\)

=\(\frac{6}{5}x\frac{7}{6}x...x\frac{2015}{2014}\)

= \(\frac{2015}{5}\)= 403.

x= 2015 hoặc 403 vì hai người kia nói hai kết quả nên tui cho là 2 đáp án

thay tui sieu khong

nếu thấy tui giỏi thì tick cho tui nhé bạn hiền

= 100x⁴

10x^2 . 10x^2

= 100x^4

-Câu cuối thôi nha bạn :v

\(B=-5x^2-4x-\dfrac{19}{5}=-5\left(x^2+\dfrac{4}{5}x+\dfrac{19}{25}\right)=-5\left(x^2+2.\dfrac{2}{5}x+\dfrac{4}{25}+\dfrac{15}{25}\right)=-5\left(x+\dfrac{2}{5}\right)^2-\dfrac{15}{5}\le-3\)\(B_{max}=-3\Leftrightarrow x=\dfrac{-2}{5}\)

3/4+2/3+5/12=11/6

7/8-7/16-11/32=3/32

3/5*2/7*5/6=1/7

15/16:3/8:3/4=10/3

bạn nhé

dấu* là nhân đó

`(x-3/5)xx3/8-5/8=1/6`

`(x-3/5)xx3/8=1/6+5/8`

`(x-3/5)xx3/8=4/24+15/24=19/24`

`x-3/5=19/24:3/8=19/9`

`x=19/9+3/5=122/45`

_______________________________________________________

`1 1/6-5/6:(x+1/4)=1/2`

`7/6-5/6:(x+1/4)=1/2`

`5/6:(x+1/4)=7/6-1/2=2/3`

`x+1/4=5/6:2/3=5/4`

`x=5/4-1/4=4/4=1`

a: \(\left(x-\dfrac{3}{5}\right)\cdot\dfrac{3}{8}-\dfrac{5}{8}=\dfrac{1}{6}\)

\(\Leftrightarrow\left(x-\dfrac{3}{5}\right)\cdot\dfrac{3}{8}=\dfrac{1}{6}+\dfrac{5}{8}=\dfrac{4}{24}+\dfrac{15}{24}=\dfrac{19}{24}\)

\(\Leftrightarrow x-\dfrac{3}{5}=\dfrac{19}{24}:\dfrac{3}{8}=\dfrac{19}{24}\cdot\dfrac{8}{3}=\dfrac{19}{9}\)

hay x=122/45

b: \(\Leftrightarrow\dfrac{7}{6}-\dfrac{5}{6}:\left(x+\dfrac{1}{4}\right)=\dfrac{1}{2}\)

\(\Leftrightarrow\dfrac{5}{6}:\left(x+\dfrac{1}{4}\right)=\dfrac{7}{6}-\dfrac{3}{6}=\dfrac{2}{3}\)

=>x+1/4=5/6:2/3=5/6x3/2=15/12=5/4

=>x=1