Tìm x a)($4x^{2}$-2$x$):2$x$-(x-3)=5 b)(x+1).(2-x)-(3x+5).(x+2)=-4$x^{2}$+1

1 bình luận về “Tìm x a)($4x^{2}$-2$x$):2$x$-(x-3)=5 b)(x+1).(2-x)-(3x+5).(x+2)=-4$x^{2}$+1”

1. Giải đáp:

   a)

   (4x^{2}-2x):2x-(x-3)=5

   <=>2x-1-x+3=5

   <=>(2x-x)+(3-1)=5

   <=>x+2=5

   <=>x=3

   Vậy x=3

   b)

   (x+1).(2-x)-(3x+5).(x+2)=-4x^{2}+1

   <=>2x-x^{2}+2-x-(3x^{2}+6x+5x+10)=-4x^{2}+1

   <=>-x^{2}+x+2-3x^{2}-11x-10=-4x^{2}+1

   <=>-4x^{2}-10x-8=-4x^{2}+1

   <=>-4x^{2}+4x^{2}-10x-8-1=0

   <=>-10x-9=0

   <=>-10x=9

   <=>x=-9/10

   Vậy x=-9/10

    

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