Question

Tính tổng:

1+2+3+5+...+89+144

Answer 1

1+2+3+5+...+89+144

= 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 ( vì 1 + 2 = 3, 2 + 3 = 5,3 + 5 = 8,...)

= 375.

Answer 2

ta có : 1+2+3+5+...+89+144

=1+2+3+5+8+13+21+34+55+89+144

= (1+2)+3+(5+8)+13+(21+34)+55+(89+144)

=3+3+13+13+55+55+233

=2(3+13+55)+233

=2*71+233

=142+233

=375

Answer 3

1+2+3+5+8+13+21+34+55+89+144

=3+3 + 13 + 13 + 55 + 55 +89 + 144

= ( 3+ 13 + 55 ) . 2 + 89 + 144

= 71 . 2 + 89 + 144

= 142 + 89 + 144

= 231 + 144

= 375