Giải phương trình 4(2x^2 +1) +3(x^2-2x)căn ( 2x-1) = 2( x^3+5x)?

By Trang Ánh Nam -

Giải pt 4(2x^2 +1) +3(x^2-2x)căn ( 2x-1) = 2( x^3+5x)?

Giải:

4(2x2+1)+3(x2-2x)=2(x3+5x)

<=>2x3-8x2+10x+4-3(x2-2x)=0

<=>(x-2)(2x2-4x-2) +3(x2-2x)=0

<=>(x-2)[ 2x2-4x+2-3x]=0

ü X=2

ü  2x2-4x+2-3x=0

Đặt u=; v=x

Thay vào ta được:

2v2-2u2-3uv=0

Vì x≥1/2 nên v>0 chia cho v2 ta được:

=>

Với 2u2v =>=x

=>2x-1=4x2

=>x2-8x+4=0

 

X=

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