Answer
(a)
$a_1=-10$
$a_2=10$
$a_3=30$
$a_4=50$
$a_5=70$
(b) $d=20$
(c) Refer to the image below for the graph.
Work Step by Step
(a) Find the first five terms of the sequence by substituting 1, 2, 3, 4, and 5 to the given formula to obtain:
$a_1=-10+20(1-1) = -10+20(0) = -10+0=-10$
$a_2=-10+20(2-1) = -10+20(1) = -10+20=10$
$a_3=-10+20(3-1) = -10+20(2) = -10+40=30$
$a_4=-10+20(4-1) = -10+20(3) = -10+60=50$
$a_5=-10+20(5-1) = -10+20(4) = -10+80=70$
(b) The common difference can be found by subtracting the first term to the second term:
$d=10-(-10)
\\d=10+10
\\d=20$
(c) Plot the points:
$(1, -10)
\\(2, 10)
\\(3, 30)
\\(4. 50)
\\(5, 70)$
Refer to the attached image in the answer part above.