Tolong bantu dengan caranya ya

1+4+7+10+...+(3n-2)=n(3n-1)/2
kita misalkan
p(1) berarti n=1
n(3n-1)/2 = 1(3.1-1)/2
= 1(2)/2
= 2/2=1
p(2) berarti n=2
n(3n-1)/2 = 2(3.2-1)/2
= 2(5)/2
= 10/2=5
p(3) berarti n=3
n(3n-1)/2 = 3(3.3-1)/2
= 3(8)/2
= 24/2= 12
p(4) berarti n=4
n(3n-1)/2 = 4(3.4-1)/2
= 4(11)/2
= 44/2=22