(8-5x).(x+2)+4.(x-2).(x+1)+2.(x-2).(x+2) Tính

2 bình luận về “(8-5x).(x+2)+4.(x-2).(x+1)+2.(x-2).(x+2) Tính”

1. (8-5x)(x+2)+4(x-2)(x+1)+2(x-2)(x+2)

   =8x+16-5x^2-10x+4(x^2+x-2x-2)+2(x^2-4)

   =8x+16-5x^2-10x+4x^2+4x-8x-8+2x^2-8

   =(8x-10x+4x-8x)+(16-8-8)-(5x^2-4x^2-2x^2)

   =-6x+x^2

   =x^2-6x

    

   Trả lời
2. Giải đáp:

   (8-5x).(x+2)+4.(x-2).(x+1)+2.(x-2).(x+2)

   =[8.(x+2)-5x.(x+2)]+4.[x.(x+1)-2.(x+1)]+2.[x.(x+2)-2.(x+2)]

   =(8x+16-5x^{2}-10x)+4.(x^{2}+x-2x-2)+2.(x^{2}+2x-2x-4)

   =(-5x^{2}-2x+16)+4.(x^{2}-x-2)+2.(x^{2}-4)

   =(-5x^{2})-2x+16+4x^{2}-4x-8+2x^{2}-8

   =(4x^{2}+2x^{2}-5x^{2})-(2x+4x)+(16-8-8)

   =x^{2}-6x

   Trả lời