Tìm x a) (2x-1)²+x(5-4x)=0 b) 4x(x-3)-3+x=0 c)x³-6x²+9x=0 d)x²-9+(x-3)²=0 e)(x+3)(x-2)-(2x-5

1 bình luận về “Tìm x a) (2x-1)²+x(5-4x)=0 b) 4x(x-3)-3+x=0 c)x³-6x²+9x=0 d)x²-9+(x-3)²=0 e)(x+3)(x-2)-(2x-5”

1. a) (2x-1)^2+x(5-4x)=0

   => 4x^2-4x+1+5x-4x^2=0

   => x+1=0

   => x=-1

   Vậy x=-1

   b) 4x(x-3)-3+x=0

   => 4x(x-3)+(x-3)=0

   => (4x+1)(x-3)=0

   TH1:

   4x+1=0

   => 4x=-1

   => x=-1/4

   TH2:

   x-3=0

   => x=3

   Vậy x∈{-1/4; 3}

   c) x^3-6x^2+9x=0

   => x(x^2-6x+9)=0

   => x(x-3)^2=0

   TH1:

   x=0

   TH2:

   (x-3)^2=0

   => x-3=0

   => x=3

   Vậy x∈{0; 3}

   d) x^2-9+(x-3)^2=0

   => (x-3)(x+3)+(x-3)^2=0

   => (x+3+x-3)(x-3)=0

   => 2x(x-3)=0

   TH1:

   2x=0

   => x=0

   TH2:

   x-3=0

   => x=3

   Vậy x∈{0; 3}

   d) (x+3)(x-2)-(2x-5)(x+3)

   =(x+3)(x-2-2x+5)

   =(x+3)(-x+3)

   =(x+3)(3-x) 

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