P = 1 + x 1 2x ( ———- ) : ( —— – ———————- ) x^2 + 1

Question

P = 1 + x 1 2x
( ———- ) : ( —— – ———————- )
x^2 + 1 x – 1 x^3 + x – x^2 – 1
cần gấp trong 5p anh azzken giup em

in progress 0
Khải Quang 4 years 2020-10-14T14:32:14+00:00 1 Answers 104 views 0

Answers ( )

  1. kiet
    0
    2020-10-14T14:33:53+00:00
    Reply

    Đáp án:

    a, Ta có : 

    `P = (x + 1)/(x^2 + 1) : (1/(x – 1) – (2x)/(x^3 + x – x^2 – 1) )`

    `= (x + 1)/(x^2 + 1) : (1/(x – 1) – (2x)/[(x^2 + 1)(x – 1)] )`

    `= [(x + 1)(x – 1)]/[(x^2 + 1)(x – 1)] : ( (x^2 + 1)/[(x – 1)(x^2 + 1)] – (2x)/[(x^2 + 1)(x – 1)] )`

    ` = [(x + 1)(x – 1)]/[(x^2 + 1)(x – 1)] : (x^2 – 2x + 1)/[(x^2 + 1)(x – 1)]`

    `= [(x + 1)(x – 1)]/[(x^2 + 1)(x – 1)] . [(x^2 + 1)(x – 1)]/(x^2 – 2x + 1)`

    `= [(x + 1)(x – 1)]/(x^2 – 2x + 1)`

    `= [(x + 1)(x – 1)]/(x – 1)^2`

    `= (x + 1)/(x – 1)`

    b, Thay `x = -1/2` vào P ta được : 

    `P = (-1/2 + 1)/(-1/2 – 1) = (1/2)/(-3/2) = 1/(-3)`

    Giải thích các bước giải:

     `x^3 + x – x^2 – 1`

    `= (x^3 + x)  – (x^2 + 1)`

    `= x(x^2 + 1) – (x^2 + 1)`

    `= (x^2 + 1)(x – 1)`

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )