Question

find the 25th term of the arithmetic sequence whose common difference is d = 4 and whose first term is a1 = - 1.

Explanation:

Step1: Recall the formula for the nth term

The formula for the $n$th term of an arithmetic sequence is $a_n=a_1+(n - 1)d$.

Step2: Identify the values of $a_1$, $n$ and $d$

Here, $a_1=-1$, $n = 25$ and $d = 4$.

Step3: Substitute the values into the formula

$a_{25}=-1+(25 - 1)\times4$.

Step4: Simplify the expression

First, calculate $25-1 = 24$. Then, $24\times4=96$. Finally, $a_{25}=-1 + 96=95$.

Answer:

$95$