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

Vậy dấu \("="\) không xảy ra

\(a,\Leftrightarrow\left(2-x\right)\left(x^2+4\right)>0\Leftrightarrow2-x>0\Leftrightarrow x< 2\\ b,\Leftrightarrow x+3>0\Leftrightarrow x>-3\\ c,\Leftrightarrow\left[{}\begin{matrix}x< -3\\x>4\end{matrix}\right.\)

b: \(\Leftrightarrow x+3>0\)

hay x>-3

tham khảo nha;

https://loga.vn/hoi-dap/tim-biet-3-5-4-2-31679

# mui #

\(x+\dfrac{3}{4}=\dfrac{28}{6}+\dfrac{1}{2}\\ x+\dfrac{3}{4}=\dfrac{31}{6}\\ x=\dfrac{31}{6}-\dfrac{3}{4}\\ x=\dfrac{53}{12}\)

\(x+\dfrac{3}{4}=\dfrac{28+3}{6}=\dfrac{31}{6}\Leftrightarrow x=\dfrac{31}{6}-\dfrac{3}{4}=\dfrac{62-9}{12}=\dfrac{53}{12}\)

B=\(\frac{2002.\left(14+1\right)-1}{2001+2002.14}\)=\(\frac{2002.14+2001}{2001+2002.14}\)=1

Giải hộ mình câu này với:

(215/216+3971/3972-1/5)x(-9/35+2/5-1/7)=..........................?

A=\(\frac{99}{28}\)

B=1

Cả lời giải đi bạn!

X - (4,5 + 2,3) = 6,9

X - 6,8 = 6,9

X = 6,9 + 6,8

X = 13,7

\(\frac{5}{8}:x=\frac{1}{2}-\frac{1}{4}\)

\(\frac{5}{8}:x=\frac{1}{4}\)

\(x=\frac{5}{8}:\frac{1}{4}\)

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

\(\frac{1}{9}:\left(x-1\right)=\frac{1}{4}\)

\(\frac{1}{9}:x-\frac{1}{9}:1=\frac{1}{4}\)

\(\frac{1}{9}:x-\frac{1}{9}=\frac{1}{4}\)

\(\frac{1}{9}:x=\frac{1}{4}+\frac{1}{9}\)

\(\frac{1}{9}:x=\frac{13}{36}\)

\(x=\frac{13}{36}:\frac{1}{9}\)

\(x=\frac{13}{4}\)

X x 2 + X x 0,3 = 0,69

X x (2 + 0,3) = 0,69

X x 2,3 = 0,69

X = 0,69 : 2,3

X = 0,3

a) x - ( 4,5 + 2,3 )= 6,9

x - 6,8  = 6,9

x = 6,9 - 6,8

x = 0,1

b)\(\frac{5}{8}\): x = \(\frac{1}{2}-\frac{1}{4}\)

\(\frac{5}{8}-x=\frac{1}{4}\)

x = \(\frac{5}{8}-\frac{1}{4}\)

x = \(\frac{3}{8}\)

c) \(\frac{1}{9}:\left(x-1\right)=\frac{1}{4}\)

x - 1 = \(\frac{1}{9}:\frac{1}{4}\)

x - 1 = \(\frac{4}{9}\)

x = \(\frac{4}{9}+1\)

x = \(\frac{13}{9}\)

d) X x 2 + X x 0,3 = 0,69

X x ( 2 + 0,3 ) = 0,69

X x 2,3 = 0,69

X = 0,69 : 2,3

X = 0,3

0,3 nhé 100 %

\(A.\left(2a+1\right)^2-4\left(a+2\right)^2=9\\ \left(2a+1-2a-4\right)\left(2a+1+2a+4\right)=9\)

\(-3\left(4a+5\right)=9\\ -12a-15=9\\ -12a=24\\ a=-2\)

\(B.\left(a+3\right)^2-\left(a-4\right)\left(a+8\right)=1\\ a^2+6a+9-\left(a^2+8a-4a-32\right)=1\)

\(a^2+6a+9-a^2-4a+32=1\\ 2a=-40\\ a=-20\)