Question 71510
Well, you don't really have an equation to solve here.  What you probably mean is..."Please help me simplify this expression"
{{{5/(2+i)}}} Multiply this by {{{(2-i)/(2-i)}}}. The {{{(2-i)}}} is the "complex conjugate" of the denominator {{{(2+i)}}}.
{{{5(2-i)/(2+i)(2-i)}}} Simplify the denominator.
{{{5(2-i)/(2^2-i^2) = 5(2-i)/(4-i^2)}}} But {{{i^2 = -1}}} so substitute in the denominator.
{{{5(2-i)/(4-(-1)) = 5(2-i)/5}}} Cancel the 5's to get:
{{{5/(2+i) = 2-i}}}