Question

Help with math

Answer 1

help QwQ

Answer 2

i'm going with b

Answer 3

the second one

Answer 4

first term=-5
c.d. d=-9-(-5)=-9+5=-4
\[a_{n}=a+(n-1)d=-5+(n-1)(-4)=-5-4n+4=-1-4n\]
\[\sum_{1}^{n}(-1-4n)\]
so b is correct.