Do 10-13 and make my life easier please answer it please

#10
[tex]\\ \sf\longmapsto 8^1=8[/tex]
#11
[tex]\\ \sf\longmapsto 1^8=1[/tex]
#12
[tex]\\ \sf\longmapsto (-5)^3=-125[/tex]
#13
[tex]\\ \sf\longmapsto (-5)^4=625[/tex]
Answer:
Tn=a+(n−1)d, where a= First term, d= Difference between terms ... (2)
Equating (1) and (2)
6n+5=a+(n−1)d
6n+5=a+nd−d ..... (3)
Equating n terms:6n=nd
d=6 ...... (4)
Substituting (4) in (3)
6n+5=a+6n−6
5=a−6
a=11 ..... (5)
Now
Sn=2n(2a+(n−1)d)
Sn=2n(a+Tn) ....... (6)
Substituting (1) and (5) in (6)
Sn=2n(11+6n+5)
Sn=2n(16+6n)
Sn=n(8+3n)