Question 283747
Hint: the first way is to expand the by either binomial expansion or just remembering that {{{(x+y)^4=(x+y)^2(x+y)^2=(x+y)(x+y)(x+y)(x+y)=(x^2+2xy+y^2)(x^2+2xy+y^2)=x^4+4x^3y+6x^2y^2+4xy^3+y^4}}}



The second way is to use <a href="http://en.wikipedia.org/wiki/De_Moivre%27s_formula">De Moivre's theorem</a> which states that {{{(cos(x)+i*sin(x))^n=cos(nx)+i*sin(nx)}}} for any complex number 'x' and integer 'n'.