Răspuns:
(2/3) (2^100-1)
Explicație pas cu pas:
(-2)(1+(-2)+(-2)²+...+(-2)^99))=
(-2) ((-2)^100-1)/(-2-1)= -2(2^100-1)/(-3) = (2/3)*(2^100-1)
altfel
-2+4=2=2^1
-8+16=8=2³
-32+64=32=2^5
............
-2^99+2^100=2^99
Suma= 2+2³+2^5+...+2^99= 2(1+2²+(2²)²+...+(2²)^49)=
=2((2²)^50-1)/(2²-1)=(2/3) (2^100-1)
