Đáp án:
Giải thích các bước giải:
(a+b+c)^3
=(a+b)^3+3(a+b)c(a+b+c)+c^3
=a^3+b^3+3ab(a+b)+3(a+b)c(a+b+c)+c^3
=a^3+b^3+c^3+ 3ab(a+b) (vì a+b+c =0)
=a^3+b^3+c^3+(-3abc) (vì a+b+c =0 nên a+b= -c)
mà a+b+c=0 nên (a+b+c)^3 =0
=> a^3+b^3+c^3+(-3abc) =0
=> a^3+b^3+c^3=3abc (đpcm)
*Bình chọn cho mình nha*
Ta có:
`a + b + c = 0`
`=> a + b = -c`
`=> (a + b)^3 = -c^3`
`<=> a^3 + 3a^{2}b + 3ab^2 + b^3 = -c^3`
`<=> a^3 + b^3 + c^3 = -3ab(a + b)`
`=> a^3 + b^3 + c^3 = -3ab.(-c)`
`=> a^3 + b^3 + c^3 = 3abc`
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Câu này sai chỗ nào và sửa lại ra sao nhỉ cả nhà ơi Machinery has made farm production easily and has liberated labor work
Thay các chữ bằng chữ số thích hợp: a, ab x ab = acc b, 1abc x 2 = abc8
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Câu 1 : Thực hiện phép tính (tính nhanh nếu có) a) 2013⁰ × 19 + 99 × 19 - (2³ : 2² + 3³ : 3) Câu 2 : a) 300 : (x + 3)² - 3 = 0
cho hình hộp chữ nhật ABCD.A’B’C’D’ có A’A=2a , ((A’BC),(ABCD))= 60° và (A’C, (ABCD)= 30°. Tính theo a thể tích khối hợp chữ nhật
Ai giỏi hình giải giúp với ạaaaaaaa Cho ∆ABC vuông tại B. Biết BC = 15cm, BA = 8cm, trên cạnh BC lấy điểm E sao cho BE = BA. a) Tính AC b) ∆ ABE là ∆ gì? Vì sao ( cái này giải y như chứng minh luôn nha ) c) Từ B kẻ đường thẳng vuông góc với AE tại H và cách AC tại D. Cm : BD là tia phân giác góc ABC d) Gọi I là giao điểm của của AB và DE. Cm : AE // IC.
Write the word the, where it is appropriate in the text, in the places indicated. (1)-------- 6.45 train, which went from Winchester to Southampton, was already full of (2) ------------commuters when Rale boarded it with fifteen minutes to go before its departure. He registered (3) ---------vague annoyance at this, as it meant he had to actually communicate with a fellow passenger in order to find (4) one remaining window seat in his normal carriage, (5) ---------carriage C. Rale always made a point of travelling in the middle carriage for (6)---------- safety's sake - about such things as (7)---------- safety he was meticulous - and would only venture into (8) first four carriages, or for that matter (9) last four, in (10) extreme emergencies. Rale was nothing if not a creature of (11) habit; it bothered him intensely if he was unable to get a window seat or if (12) drinks trolley lady didn't come round, or worse still, she came but (13) hot water boiler wasn't working and so (14) coffee was not available. A brioche and a cup of coffee - black, one sugar - was Rale's early-morning indulgence. He found it sufficed for a breakfast, unless he was unusually hungry. Exactly ten minutes into (15) journey, Rale opened his briefcase and took out his copy of that morning's Guardian newspaper, neatly folded, and began (16) crossword. This was (17) time of day Rale liked best. He could immerse himself in (18) delightful challenge of teasing out words from his mind, and put off (19) thoughts of work in the administrative department of (20) Southampton Hospital. Today, however, Rale's neatly planned existence was to be well and truly turned on its head.
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