\(c,\left(x+2\right)^2+\left(x-1\right)\left(x+3\right)=2\left(x-4\right)\left(x+4\right)\\ \Leftrightarrow x^2+4x+4+x^2+2x-3=2\left(x^2-16\right)\\ \Leftrightarrow2x^2+6x+1=2x^2-32\\ \Leftrightarrow6x=-33\\ \Leftrightarrow x=-\dfrac{11}{2}\)

c, ĐKXĐ:\(x\ne-1\)

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

\(\Rightarrow x^2-x+1+2x^2+1+2x^4-2x^2-2x^4-2x=0\\ \Leftrightarrow x^2-3x+2=0\\ \Leftrightarrow\left(x-1\right)\left(x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=1\left(tm\right)\\x=2\left(tm\right)\end{matrix}\right.\)

ĐKXĐ:\(x,y\ne0\)

Đặt \(\dfrac{1}{\sqrt{x}}=a,\dfrac{1}{\sqrt{y}}=b\)

\(Hệ\Leftrightarrow\left\{{}\begin{matrix}7a-4b=\dfrac{5}{3}\\5a+3b=\dfrac{13}{6}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}a=\dfrac{1}{3}\\b=\dfrac{1}{6}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{\sqrt{x}}=\dfrac{1}{3}\\\dfrac{1}{\sqrt{y}}=\dfrac{1}{6}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}\sqrt{x}=3\\\sqrt{y}=6\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=9\\y=36\left(tm\right)\end{matrix}\right.\)

\(\dfrac{-3}{8}.\dfrac{17}{31}.\dfrac{-16}{9}.\dfrac{-93}{34}\\ =\dfrac{\left(-3\right).17.\left(-16\right).\left(-93\right)}{8.31.9.34}\\ =\dfrac{-\left(3.17.8.2.31.3\right)}{8.31.3.3.17.2}\\ =-1\)

Độ dài của hình thoi đó là:
`120xx2:16=15(m)`

Đáp số: 15m

\(a,\dfrac{5\left(1-2x\right)}{3}+\dfrac{x}{2}=\dfrac{3\left(x-5\right)}{4}-2\\ \Leftrightarrow\dfrac{20\left(1-2x\right)}{12}+\dfrac{6x}{12}-\dfrac{9\left(x-5\right)}{12}+\dfrac{24}{12}=0\\ \Leftrightarrow20-40x+6x-9x+45+24=0\\ \Leftrightarrow-43x+89=0\\ \Leftrightarrow x=\dfrac{89}{43}\)

b, ĐKXĐ:\(x\ne\pm1\)

\(\dfrac{3}{x-1}=\dfrac{3x+2}{1-x^2}-\dfrac{4}{x+1}\\ \Leftrightarrow\dfrac{3\left(x+1\right)}{\left(x+1\right)\left(x-1\right)}+\dfrac{3x+2}{\left(x+1\right)\left(x-1\right)}+\dfrac{4\left(x-1\right)}{\left(x+1\right)\left(x-1\right)}=0\\ \Leftrightarrow\dfrac{3x+3+3x+2+4x-4}{\left(x+1\right)\left(x-1\right)}=0\\ \Rightarrow10x+1=0\\ \Leftrightarrow x=-\dfrac{1}{10}\left(tm\right)\)

`x xx 45,2 - x xx 15,2=4,5`

`x xx (45,2-15,2)=4,5`

`x xx 30= 4,5`

` x = 4,5:30`

`x=0,15`

Lớp 6A có số học sinh nữ là:

`44xx6/11=24`(học sinh)

Lớp 6A có số học sinh nam là:

`44-24=20`(học sinh)

Đáp số: ...

Trang trại đó nuôi được số con gà là:
`3420:(4+5)xx4=1520`(con gà)

Trang trại đó nuôi được số con vịt là:

`3420-1520=1900`(con vịt)

Đáp số:...

Bạn đăng nhỏ câu hỏi ra nhé

Chiều cao hình bình hành là:

`180:45=4(m)`

Đáp số: 4m