Question

KHẨN CẤP!!!

(2+4+6+8+...+98+100)x 10/2+4+8+16+...+512-2

Answer 1

(2+4+6+8+...+98+100)x 10/2+4+8+16+...+512-2
Ta có: 
+) 2 + 4 + 6 + 8 + ... + 98 + 100
= (100 + 2)[(100 - 2) : 2 + 1] : 2
= 102.50:2 = 2550
+)Dặt A = 2 + 4 + 8 + 16 + ... + 512 - 2
A = 2 + 2^2 + 2^3 + 2^4 + ... + 2^9 - 2
A = 2^2 + 2^3 + 2^4 + ... + 2^9
2A = 2(2^2 + 2^3 + 2^4 + .... + 2^9)
2A = 2^3 + 2^4 + 2^5 + ... + 2^10
2A - A = (2^3 + 2^4  + 2^5 + ... + 2^10) - (2^2 + 2^3 + 2^4 + ... + 2^9)
A =  2^10 - 2^2
A = 1024 - 4 = 1020
=> (2 + 4 + 6 + 8 + ... + 98 + 100) x 10/2 + 4 + 8 + 16 + ... + 512 - 2
  = 2550 x 10/1020 = 25500/1020 = 25

Answer 2

chịu thôi

Answer 3

25 nhaaaaaaaaaaaaaaaaaaaaaaaaaaaa