How to solve in an arithmetic series/sequence

Question

Q: Find a_37 if a_1= -21 and d= -5

I am confused as to how I would find the answer by plugging in values to the arithmetic series formula.

Answer 1

Stratton

In an arithmetic series a_n=a + (n-1) d, a is the first term (a₁) , d is the common difference, and n the term number.

So you know a = -21, and d = -5. To find a₃₇ just set n = 37.

Then put these 3 values into the above expression.

a₃₇ = (-21) + (37-1) (-5)

Mike

Answer 2

a_n = a₁ + (n - 1)(d)

a₃₇ = -21 + (36)(-5)

a₃₇ = -201