Answer:
Step-by-step explanation:
[tex]an = -3n - 1\\a1 = -3(1)-1=-4\\a2=-3(2)-1=-7\\a3=-3(3)-1=-10\\a4=-3(4)-1=-13\\a5= -3(5)-1=-16[/tex]
[tex]Sn =\frac{n(a1+an)}{2} \\Sn=\frac{5(-4-16)}{2} \\Sn=\frac{5(-20)}{2} \\Sn=\frac{-100}{2} \\Sn=-50[/tex]
