Answer:
28
Step-by-step explanation:
Let n = 21, and evaluate the expression.
[tex] a_n = -2 + \dfrac{3}{2}(n - 1) [/tex]
[tex] a_{21} = -2 + \dfrac{3}{2}(21 - 1) [/tex]
[tex] a_{21} = -2 + \dfrac{3}{2}(20) [/tex]
[tex] a_{21} = -2 + \dfrac{3}{1}(10) [/tex]
[tex] a_{21} = -2 + 30 [/tex]
[tex] a_{21} = 28 [/tex]
