a, (x+1) (x²-x+1) – x(x²-2)=9 b, 2x(x+3) – (x-5) (7+2x)=44 c, (2x+3) (x²+x) – 2x(x²+5x/2=9 d, (x²-3x) (2x-1) – x(2x²-7x)=12 e, (x+2) (x²-4x+1) – ( x³-

a, (x+1) (x²-x+1) – x(x²-2)=9
b, 2x(x+3) – (x-5) (7+2x)=44
c, (2x+3) (x²+x) – 2x(x²+5x/2=9
d, (x²-3x) (2x-1) – x(2x²-7x)=12
e, (x+2) (x²-4x+1) – ( x³-2x²+2)= -18

0 bình luận về “a, (x+1) (x²-x+1) – x(x²-2)=9 b, 2x(x+3) – (x-5) (7+2x)=44 c, (2x+3) (x²+x) – 2x(x²+5x/2=9 d, (x²-3x) (2x-1) – x(2x²-7x)=12 e, (x+2) (x²-4x+1) – ( x³-”

  1. Đáp án:

     `a) x=4`

     `b) x=1`

     `c) x=3`

     `d) x=4`

     `e) x=3`

    Giải thích các bước giải:

     a)

    `(x+1)(x^2 -x+1)-x(x^2 -2)=9`

    `<=> x^3 + 1 – x^3 + 2x=9`

    `<=> 2x=8`

    `<=> x=4`

    b)

    `2x(x+3)-(x-5)(7+2x)=44`

    `<=> 2x^2 + 6x – (7x +2x^2 -35 -10x)=44`

    `<=> 2x^2 + 6x – 7x – 2x^2 + 35 + 10x = 44`

    `<=> 9x + 35 = 44`

    `<=> 9x = 9`

    `<=> x=1`

    c)

    `(2x+3)(x^2 + x)- 2x(x^2 + (5x)/2)=9`

    `<=> 2x^3 + 2x^2 + 3x^2 + 3x – 2x^3 – 5x^2 =9`

    `<=> 3x = 9`

    `<=> x=3`

    d)

    `(x^2 – 3x)(2x – 1) – x(2x^2 – 7x) = 12`

    `<=> 2x^3 – x^2 – 6x^2 + 3x – 2x^3 + 7x^2 = 12`

    `<=> 3x = 12`

    `<=> x=4`

    e)

    `(x + 2)(x^2 – 4x +1) – (x^3 – 2x^2 + 2)= -18`

    `<=> x^3 – 4x^2 + x +2x^2 – 8x + 2 – x^3 +2x^2 -2 = -18`

    `<=> -6x = -18`

    `<=> x=3`

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