Let {an} be an equal ratio sequence with the first term of 1 and the common ratio of - 2, then a1 + | A2 | + a3 + | A4|

Let {an} be an equal ratio sequence with the first term of 1 and the common ratio of - 2, then a1 + | A2 | + a3 + | A4|

a1+|a2|+a3+|a4|
=1+2+4+8
=15