## Precalculus (6th Edition) Blitzer

$a_1=7;a_2 =11, a_3= 15; a_4=19; a_5= 23: a_6=27$
We need to use the formula: $a_n =a_1+(n-1) d$ ....(1) Here, $a_1=7$ and $d=4$ Plug in: $n=1,2,3,4,5,6$ In order to calculate the first $6$ terms of the sequence, we will have to plug $n=1,2,3,4$ into the given equation (1). $a_1=7 +(1-1) \times 4 =7; a_2=7 +(2-1) \times 4 =7+4=11$; $a_3=7 +(3-1) \times 4 =15$ ; $a_4=7 +(4-1) \times 4 =19$; $a_5=7 +(5-1) \times 4 =23$ ; $a_6=7 +(6-1) \times 4 =7+20=27$ So, the first $6$ terms are: $a_1=7;a_2 =11, a_3= 15; a_4=19; a_5= 23: a_6=27$