tìm x a) (4x+5)^2-(4x+3)(4x-3)=89 b) 2x(x-25)+(25-x)=0

1 bình luận về “tìm x a) (4x+5)^2-(4x+3)(4x-3)=89 b) 2x(x-25)+(25-x)=0”

1. a) (4x+5)^2-(4x+3)(4x-3)=89

   => 16x^2+40x+25-(16x^2-9)=89

   => 16x^2+40x+25-16x^2+9-89=0

   => 40x-55=0

   => 40x=55

   => x=11/8

   Vậy x=11/8

   b) 2x(x-25)+(25-x)=0

   => 2x(x-25)-(x-25)=0

   => (2x-1)(x-25)=0

   TH1:

   2x-1=0

   => 2x=1

   =>x=1/2

   TH2:

   x-25=0

   => x=25

   Vậy x∈{1/2; 25}

   Trả lời