\(a,A=\left(x^2-x\right)\left(x^2-x-12\right)\\ A=\left(x^2-x\right)^2-12\left(x^2-x\right)\\ A=\left(x^2-x\right)^2-12\left(x^2-x\right)+36-36\\ A=\left(x^2-x+6\right)^2-36\ge-36\\ A_{min}=-36\Leftrightarrow x^2-x+6=0\Leftrightarrow\left(x-3\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\\ b,B=4x^4+4x^3+5x^2+4x+3\\ B=\left(4x^4+4x^3+x^2\right)+\left(x^2+4x+4\right)-1\\ B=x^2\left(2x+1\right)^2+\left(x+2\right)^2-1\ge-1\\ B_{min}=-1\Leftrightarrow\left\{{}\begin{matrix}x\left(2x+1\right)=0\\x+2=0\end{matrix}\right.\Leftrightarrow x\in\varnothing\)

Vậy dấu \("="\) không xảy ra

Bn thông cảm.Bài này mn ko bt làm

\(\Leftrightarrow-\dfrac{2}{5}\left(4x-3\right)^2=-\dfrac{5}{18}\)

\(\Leftrightarrow\left(4x-3\right)^2=\dfrac{25}{36}\)

\(\Leftrightarrow4x-3\in\left\{\dfrac{5}{6};-\dfrac{5}{6}\right\}\)

hay \(x\in\left\{\dfrac{23}{24};\dfrac{13}{24}\right\}\)

          x² + 4x + 3 = 0

\(\Leftrightarrow\)x² + x + 3x + 3 = 0

\(\Leftrightarrow\)x(x + 1) + 3(x + 1) = 0

\(\Leftrightarrow\)(x + 1)(x + 3) = 0

\(\Leftrightarrow\)\(\orbr{\begin{cases}x+1=0\\x+3=0\end{cases}}\)\(\Leftrightarrow\)\(\orbr{\begin{cases}x=-1\\x=-3\end{cases}}\)

          Vậy....

1wwqewqerwrewr

\(x^2+4x+3=0\)

\(x^2+x+3x+3=0\)

\(\left(x^2+x\right)+\left(3x+3\right)=0\)

\(x\left(x+1\right)+3\left(x+1\right)=0\)

\(\left(x+1\right).\left(x+3\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+1=0\\x+3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-1\\x=-3\end{cases}}}\)

Vậy x=-1 hoặc x=-3

chọn mk nha

\(a,\Leftrightarrow\left[{}\begin{matrix}x-8=0\\x^3+8=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=8\\x^3=-8\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=8\\x=-2\end{matrix}\right.\\ b,\Leftrightarrow4x-3-x-5=30-3x\\ \Leftrightarrow4x-x+3x=30+5+3\\ \Leftrightarrow6x=38\\ \Leftrightarrow x=\dfrac{19}{3}\)

câu a+b dùng quy tắc chuyển vế

c, 3.(1/2-x)-5.(x-1/10)=-7/4

=>(3.1/2-3x)-(5x-5.1/10)=-7/4

=>3/2-3x-5x+1/2=-7/4

=>(3/2+1/2)-(3x+5x)=-7/4

=> 2-8x=-7/4

=>8x=15/4

=>x=15/4:8

=>x=15/32

a) 2.(1/4 - 3x) = 1/5 - 4x
=> 1/2 - 6x = 1/5 -4x
=> -6x + 4x = 1/5 - 1/2
=> -2x         = -3/10 = 3/20
b) 4.(1/3 - x) + 1/2 = 5/6 +x 
=> 4/3 - 4x + 1/2 = 5/6 +x
=> -4x - x = 5/6 - 4/3 - 1/2
=> -5x = -1
=> x= 1/5
c) 3. (1/2 - x) -5. ( x - 1/10) = -7/4
=> 3/2 - 3x - 5x + 1/2 = -7/4
=> -3x - 5x = -7/4 - 3/2 - 1/2 
=> -8x = -15/4
=> x = 15/32

mình chịu

x= -3/4 nhé bạn

Trả lời:

4x+18/4 =3/2

-> 4x + 9/2=3/2

-> 4x = -6/2= -3

-> x=-3/4

\(4x+\frac{18}{4}=\frac{3}{2}\)

\(4x=\frac{3}{2}-\frac{9}{2}\)

\(4x=-\frac{6}{2}\)

    \(x=-\frac{6}{2}:4\)

    \(x=-\frac{6}{8}=-\frac{3}{4}\)

4x + 5 : 3 - 121 : 11 

=4 . 4 + 5 : 3 - 121 : 11

= 16 + \(\frac{5}{3}\) - 11

= \(\frac{20}{3}\)