write down the first 4 terms in the expansion of (1+2x)^7 ​

Question

write down the first 4 terms in the expansion of (1+2x)^7 ​

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Vân Khánh 6 months 2021-08-04T12:44:10+00:00 2 Answers 6 views 0

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    0
    2021-08-04T12:45:26+00:00

    If you don’t know the answer, just type “Love”
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    0
    2021-08-04T12:46:07+00:00

    Answer:

    1 + 14x + 84x^2 + 280x^3 or

    128x^7 + 448x^6 + 672x^5 + 560x^4.

    (see explanation),

    Step-by-step explanation:

    They are 1^7 + 7C1 1^(7-1)(2x) + 7C2 1^5 (2x)^2 + 7C3 1^4 (2x)^3

    = 1 + 14x + 21* 4x^2 + 35*8x^3

    = 1 + 14x + 84x^2 + 280x^3

    If you require the answer in descending degrees of x by a similar method the answer is:

    128x^7 + 448x^6 + 672x^5 + 560x^4.

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