Question

Find the first, fourth, and tenth terms of the arithmetic sequence described by the given rule A(n)=-3+(n-1)(-2.2)

Answer 1

$A(n)=-3+(n-1)(-2.2)=-3+(n)(-2.2)+(-1)(-2.2)\\\\A(n)=-3-2.2n+2.2=-0.8-2.2n\\\\\text{Substitute n = 1, n = 4, n = 10}:\\\\A(1)=-0.8-2.2(1)=-0.8-2.2=-3\\\\A(4)=-0.8-2.2(4)=-0.8-2.2(4)=-0.8-8.8=-9.6\\\\A(10)=-0.8-2.2(10)=-0.8-22=-22.8$