= 2 + 22 + 23 + 24 + .... + 29
Đặt A = 2 + 22 + 23 + 24 + .... + 29
nhân hai vào A ta được :
2A = 2.( 2 + 22 + 23 + 24 + .... + 29 )
=> 2A = 22 + 23 + 24 + 25 + .... + 210
Lấy biểu thước 2A trừ A ta được :
2A - A = ( 22 + 23 + 24 + 25 + .... + 210 ) - ( 2 + 22 + 23 + 24 + .... + 29 )
=> A = 210 - 2
=> A = 1022
a) 2+4+8+16+32+64+128+256+512+1024+2048
b) \(\frac{\left(2+4+6+8+...+1000\right)nhan10}{2+4+8+16+...+512-2}\)
1+2+4+8+16+32+...+256+512 =
Tính nhanh tổng a,1+4+9+16+25+....+144+169. b,1+2+4+8+16+32+........+256+512+1024
1+ 1/2 + 1/4 + 1/8 + 1/16+ 1/32 +1/64 + .... + 1/512 +1/1024
Tính nhanh:
1+2+4+8+16+32+.......+256+512+1024
b,1+4+9+16+25+........+144+169
1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256+1/512+/1024
Tính nhanh : 1+1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256+1/512
1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/256+1/512+1/1024 =?
