Answer:
n = 1
Step-by-step explanation:
n(n - 4) + n(n + 8) = n(n - 13) + n(n+1) + 16
n^2 - 4n + n^2 + 8n = n^2 - 13n + n^2 + n + 16
n^4 + 4n = n^4 - 12n + 16
n^4 - n^4 + 4n + 12n - 16 = 0
16n - 16 = 0
16n = 16
n = 16/16
n = 1
better check this...
1(1 - 4) + 1(1 + 8) = 1(1 - 13) + 1(1 + 1) + 16
1(-3) + 1(9) = 1(-12) + 1(2) + 16
-3 + 9 = -12 + 2 + 16
6 = 4 + 2
6 = 6 (correct)...so it checks out
