Toán Phương trình, hệ phương trình

Erwin Schrödinger said:

a) [tex]x(4x^2+x)+4x^2+x=\sqrt{3x+1}-2x-1<=>(4x^2+x)(x+1)=\frac{3x+1-4x^2-4x-1}{\sqrt{3x+1}+2x+1}=\frac{-4x^2-x}{\sqrt{3x+1}+2x+1}=>4x^2+x=0\vee x+1+\frac{1}{\sqrt{3x+1}+2x+1}=0[/tex]
[tex]x+1+\frac{1}{\sqrt{3x+1}+2x+1}>0,\forall x\geq \frac{-1}{3}[/tex]
b) [tex]2y^4(x-3)(5x-2)=-3(5x-2)=>5x-2=0 \vee 2y^4(x-3)=-3[/tex]
=> [tex]\frac{6-15x}{5x^2-17x+6}\geq 0 <=> \frac{2}{5}<x<3 [tex] => [tex]y^4=\frac{3}{2(3-x)}[/tex]
=>[/tex][/tex]

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