Câu hỏi của Hòa Phan

Question

1 x 2 x 3 + 2 x 3 x 4 + ..... + 98 x 99 x 100

Trần Minh Hoàng · Accepted Answer

Đặt A = 1 . 2 . 3 + 2 . 3 . 4 + ... + 98 . 99 . 100

$\Rightarrow$ 4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . (5 - 1) +...+ 98 . 99 . 100 . (101 - 97)

$\Rightarrow$ 4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . 5 - 2 . 3 . 4 . 1 + ... + 98 . 99 . 100 . 101 - 98 . 99 . 100 . 97

$\Rightarrow$ 4A = 98 . 99 . 100 . 101

$\Rightarrow$ 4A = 97990200

$\Rightarrow$ A = 24497550Câu trả lời: Đặt A = 1 . 2 . 3 + 2 . 3 . 4 + ... + 98 . 99 . 100

$\Rightarrow$ 4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . (5 - 1) +...+ 98 . 99 . 100 . (101 - 97)

$\Rightarrow$ 4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . 5 - 2 . 3 . 4 . 1 + ... + 98 . 99 . 100 . 101 - 98 . 99 . 100 . 97

$\Rightarrow$ 4A = 98 . 99 . 100 . 101

$\Rightarrow$ 4A = 97990200

$\Rightarrow$ A = 24497550

Quốc Huy · Answer

Đặt A = 1 . 2 . 3 + 2 . 3 . 4 + ... + 98 . 99 . 100

=>4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . (5 - 1) +...+ 98 . 99 . 100 . (101 - 97)

=>4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . 5 - 2 . 3 . 4 . 1 + ... + 98 . 99 . 100 . 101 - 98 . 99 . 100 . 97

=>4A = 98 . 99 . 100 . 101 4A = 97990200

=>A = 24497550

Vậy A= 24497550Câu trả lời: Đặt A = 1 . 2 . 3 + 2 . 3 . 4 + ... + 98 . 99 . 100

=>4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . (5 - 1) +...+ 98 . 99 . 100 . (101 - 97)

=>4A = 1 . 2 . 3 . 4 + 2 . 3 . 4 . 5 - 2 . 3 . 4 . 1 + ... + 98 . 99 . 100 . 101 - 98 . 99 . 100 . 97

=>4A = 98 . 99 . 100 . 101 4A = 97990200

=>A = 24497550

Vậy A= 24497550

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