Respuesta :

Answer: -20

Step-by-step explanation:where first term =a and common difference=d

[tex]S_{n} =\frac{n}{2} [2a+(n-1)d][/tex]

     =[tex]\frac{4}{2} [2*(-2)+(4-1)*-2][/tex]

     =[tex]\frac{4}{2} *-10[/tex]

     =[tex]-20[/tex]