Tính:

\(\frac{1}{1+\frac{2013}{2014}+\frac{2013}{2015}}+\frac{1}{1+\frac{2014}{2015}+\frac{2014}{2013}}+\frac{1}{1+\frac{2015}{2013}+\frac{2015}{2014}}\)

Isambard Kingdom Brunel was a famous nineteenth-century engineer. He (1) _________ born in 1806 in Portsmouth, a seaport in the South of England. In 1923, after studying (2) _________ two years in Paris, he started (3) _________ for his father, (4) _________ was an engineer and inventor. He had been born near Rouen in France but in 1792 had left France for the US and had later settled in England. Both father and son were responsible for the design (5) _________ construction of the first tunnel under the River Thames. The digging of this tunnel was (6) _________ in 1825 and completed twenty years later. Today, it (7) _________ part of the London Underground system.

Isambard Kingdom Brunel went (8) _________ to design the Great Britain (1845), (9) _________ was the first large ship to be built (10) _________ iron instead of wood. It was powered (11) _________ steam and made regular crossings of the Atlantic. Remarkably, this ship is (12) _________ in existence. It (13) _________ been restored and can be seen in Bristol (14) _________ it was originally built. (15) _________ of Brunel’s great engineering achievements was the construction of the Great Western Railway from London to Bristol. He designed all the stations, bridges, tunnel and viaducts along the line.

Brunel’s ideas were ahead of his time and had difficulties in convincing people that they were realistic, and, indeed, some of his projects were very ambitious, but he (16) _________ determined to find (17) _________ to the (18) _________ difficult problems. Overwork ruined his health and he (19) _________ at the age of fifty-two in 1859. The work of Brunel, and his father, has always been highly regarded and Brunel University, founded in 1966, is (20) _________ after both of them.

Ba điểm O, A, B thuộc đường thẳng xy. Tính độ dài đoạn thẳng AB biết OA + OB = a và OA - OB = b, (0<b <a).

Một quả bóng bay thẳng vào kính và làm vỡ. Thầy giám thị gọi bốn bạn học sinh lên tình nghi để điều tra.

An: Dũng đã làm vỡ kính ạ

Bình: Dũng đã làm vỡ kính ạ

Cường: Em không làm vỡ kính

Dũng: Bình nói dối đấy a

Biết rằng chỉ có một người nói thật, hỏi ai làm vỡ kính

Tìm tất cả số tự nhiên lớn hơn 10000 nhưng nhỏ hơn 15000 mà khi chia 2015 cũng như khi chia cho 25 đều được số dư là 10

Cho hai tập hợp A={x €N|5+x<18} và B = {x €N|x>8}

Có bao nhiêu tập hợp có 3 phần tử vừa là tập con của A vừa là tập con của B

It's...(possible) to see her at this time. It is too late

midnight, and my husband (not arrive) home and (not telephone) ! I'm beginning to be very worried. he (say) this morning that he (be) home for dinner as usual