`2) x^3 -9x^2+6x+16` `3) x^3-6x^2-x+30` `4)2x^3-x^2+5x+3` `5)27x^3-27x^2+18x-4`

2 bình luận về “`2) x^3 -9x^2+6x+16` `3) x^3-6x^2-x+30` `4)2x^3-x^2+5x+3` `5)27x^3-27x^2+18x-4`”

1. Giải đáp+Lời giải và giải thích chi tiết:

   2) x^3 – 9x^2 + 6x + 16

   = x^3 + x^2 – 10x^2 – 10x + 16x + 16

   = x^2 ( x+1) – 10 (x+1) + 16 (x+1)

   = (x+1)(x^2 – 10x + 16)

   = (x+1)(x^2 – 2x – 8x +16)

   = (x+1)[x(x-2) – 8(x-2)]

   = (x+1)(x-2)(x-8)

   3) x^3 – 6x^2 – x + 30

   = x^3 + 2x^2 – 8x^2 – 16x + 15x + 30 

   = x^2 (x+2) – 8x (x+2) + 15 (x+2)

   = (x+2)(x^2 – 8x + 15)

   = (x+2)(x^2 – 3x – 5x +15)

   = (x+2)[x(x-3) – 5(x-3)]

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

   4) 2x^3 – x^2 + 5x + 3

   = 2x^3 + x^2 – 2x^2 – x + 6x + 3

   = x^2 (2x+1) -x (2x+1) + 3 (2x+1)

   = (2x+1)(x^2 – x + 3)

   5) 27x^3 – 27x^2 + 18x – 4

   = 27x^3 – 9x^2 – 18x^2 + 6x + 12x – 4

   = 9x^2 (3x-1) -6x (3x-1) + 4 (3x-1)

   = (3x-1)(9x^2 – 6x + 4)

   #Darkshadow169

   Trả lời
2. Giải đáp+Lời giải và giải thích chi tiết:

    2)

   x^{3}-9x^{2}+6x+16

   =x^{3}+x^{2}-10x^{2}+16x-10x+16

   =x^{2}.(x+1)-10x.(x+1)+16.(x+1)

   =(x+1).(x^{2}-10x+16)

   =(x+1).(x^{2}-2x-8x+16)

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

   =(x+1).(x-2).(x-8)

   3)

   x^{3}-6x^{2}-x+30

   =x^{3}+2x^{2}-8x^{2}-16x+15x+30

   =x^{2}.(x+2)-8x.(x+2)+15.(x+2)

   =(x+2).(x^{2}-8x+15)

   =(x+2).(x^{2}-3x-5x+15)

   =(x+2).[x.(x-3)-5.(x-3)]

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

   4)

   2x^{3}-x^{2}+5x+3

   =2x^{3}+x^{2}-2x^{2}+6x-x+3

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

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

   5)

   27x^{3}-27x^{2}+18x-4

   =27x^{3}+12x+6x-9x^{2}-18x^{2}-4

   =(27x^{3}-9x^{2})+(12x-4)+(6x-18x^{2})

   =9x^{2}.(3x-1)+4.(3x-1)+6x.(1-3x)

   =(3x-1).(9x^{2}+4)-6x.(3x-1)

   =(3x-1).(9x^{2}-6x+4)

   Trả lời