Answer
$0$
Work Step by Step
Use the rule $a^{mn}=\left(a^m\right)^n$ to obtain:
$i^7+i^5+i^3+i\\
=i^6\cdot i+i^4\cdot i+i^3+i\\
=(i^2)^3\cdot i+i^4\cdot i+i^3+i$
Use $i^2=-1,i^3=-i$ and $i^4=i$ then simplify.
$=(-1)^3\cdot i+1\cdot i+(-i)+i$
$=-i+i-i+i$
$=0$
Hence, the solution in the standard form is $0$.
