Beth B. answered • 05/09/21
Math Tutor w/ over 2 years of teaching experience ready to help!
If a1= 3 and the recursive formula for this problem is:
an = 1 + an-1 -7
Start by plugging in what we know: that a1 = 3. Wherever we see a subscript of n, we will substitute the number 1 and wherever we see "an" we will substitute the number 3.
3 = 1 + a1 - 1 - 7
3 = 1 + a0 - 7
3 = a0 +1 - 7
3 = a0 - 6
+6 +6
9 = a0 or a0 = 9
a2 = 1 + a2-1 - 7
a2 = 1 + 3 - 7
a2 = 4 - 7
a2 = - 3
a3 = 1 + a2 -7
a3 = 1 + (-3) - 7
a3 = 1 - 3 - 7
a3 = - 9
a4 = 1 + a3 -7
a4 = 1 + (-9) - 7
a4 = 1 - 9 - 7
a4 = -15
