3x.(x-5)-5x(x+7) -4x.(3x-4)+7x.(x-5) x.(2x ²-3)-x ².(5x+1)+x ² 3x.(x-2) – 5x.(1-x)-8.(x ² -3)

2 bình luận về “3x.(x-5)-5x(x+7) -4x.(3x-4)+7x.(x-5) x.(2x ²-3)-x ².(5x+1)+x ² 3x.(x-2) – 5x.(1-x)-8.(x ² -3)”

1. Giải đáp:

   1) -2x^2-50x

   2) -5x^2-19x

   3) -3x^3-3x

   4) -11x+24

   Lời giải và giải thích chi tiết:

   1) 3x(x-5)-5x(x+7)

   = 3x. x-3x. 5-5x. x-5x. 7

   = 3x^2-15x-5x^2-35x

   = (3x^2-5x^2)+(-15x-35x)

   = -2x^2-50x

   ———-

   2) -4x(3x-4)+7x(x-5)

   = -4x. 3x-4x. (-4)+7x. x+7x. (-5)

   = -12x^2+16x+7x^2-35x

   = (-12x^2+7x^2)+(16x-35x)

   = -5x^2-19x

   ———-

   3) x(2x^2-3)-x^2(5x+1)+x^2

   = x. 2x^2-x. 3-x^2. 5x-x^2. 1+x^2

   = 2x^3-3x-5x^3-x^2+x^2

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

   = -3x^3-3x

   ———-

   4) 3x(x-2)-5x(1-x)-8(x^2-3)

   = 3x. x-3x. 2-5x. 1-5x. (-x)-8. x^2-8. (-3)

   = 3x^2-6x-5x+5x^2-8x^2+24

   = (3x^2+5x^2-8x^2)+(-6x-5x)+24

   = -11x+24

    

   Trả lời
2. 3x(x – 5) – 5x(x + 7)

   = 3x^2 – 15x – 5x^2 – 35x

   = -2x^2 – 50x

   —————-

   -4x(3x – 4) + 7x(x – 5)

   = -12x^2 + 16x + 7x^2 – 35x

   = -5x^2 – 19x

   —————

   x(2x^2 – 3) – x^2 (5x + 1) + x^2

   = 2x^3 – 3x – 5x^3 – x^2 + x^2

   = -3x^3 – 3x

   ———

   3x(x – 2) – 5x(1 – x) – 8(x^2 – 3)

   = 3x^2 – 6x – 5x + 5x^2 – 8x^2 + 24

   =-11x + 24
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   Trả lời