## College Algebra 7th Edition

A) To add complex numbers we add the real parts and imaginary parts separately. B) Multiplying is like expanding binomial expressions, and substituting $i^2=-1$ $(2+5I)(2-i)=10i-3i-5*i^2+6 = =(10-3)i-5*(-1)+6 = 11+7i$ C) Yes as the expression becomes $9-i^2 = 10$ D) Multiply the numerator and denominator by $3+i$ which is the conjugate of the denominator.