chụp rõ hơn một xíu đc ko bạn

3:

a: \(P\left(x\right)=2x^4+2x^3-5x+3\)

\(Q\left(x\right)=4x^4-2x^3+2x^2+5x-2\)

b: P(-1)=2-2-3+5+3=5

Q(0)=4*0-2*0+2*0+5*0-2=-2

c: G(x)=2x^4+2x^3-5x+3+4x^4-2x^3+2x^2+5x-2

=6x^4+2x^2+1

d: G(x)=x^2(6x^2+2)+1>0 với mọi x

\(2x^3+5x^2-3x=0\Leftrightarrow x\left(2x^2+5x-3\right)=0\Leftrightarrow x\left(2x-1\right)\left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\\x=-3\end{matrix}\right.\)

b: \(\Leftrightarrow8\left(1-3x\right)-2\left(3x+2\right)=140-15\left(2x+1\right)\)

=>8-24x-6x-4=140-30x-15

=>-30x+30x=115-4=111

=>0x=111(vô lý)

làm hộ luôn câu 4

câu d

c) \(pt\Leftrightarrow\dfrac{5\left(5x+2\right)-10\left(8x-1\right)-6\left(4x+2\right)-30}{30}=0\Leftrightarrow-79x-22=0\Leftrightarrow x=-\dfrac{22}{79}\)

d) \(pt\Leftrightarrow\dfrac{3\left(3x+2\right)-3x-1-6.2x+5.2}{6}=0\Leftrightarrow-6x+15=0\Leftrightarrow x=\dfrac{15}{6}\)

\(\dfrac{2x+1}{x-1}< 1\)

\(\dfrac{2x+1}{x-1}-1< 0\)

\(\dfrac{2x+1-x+1}{x-1}< 0\)

\(\dfrac{x+2}{x-1}< 0\)

\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x+2< 0\\x-1>0\end{matrix}\right.\\\left\{{}\begin{matrix}x+2>0\\x-1< 0\end{matrix}\right.\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< -2\\x>1\end{matrix}\right.\\\left\{{}\begin{matrix}x>-2\\x< 1\end{matrix}\right.\end{matrix}\right.\) 

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