Question

I will give brainliest to the best response. I would really like help solving this problem.

Answer 1

Answer:

Step-by-step explanation:

given

first term(a)=4

last term (l)=(5n-1)

now

$S_{n}$=$\frac{n}{2}$(a+l)

$\frac{n(3+5n)}{2}$=$\frac{n}{2}$(a+l)

$\frac{n(3+5n)}{2}$=$\frac{n}{2}$(4+5n-1)

$\frac{n(3+5n)}{2}$=$\frac{n}{2}$(5n+3)

$\frac{n(3+5n)}{2}$=$\frac{n(3+5n)}{2}$ true