Answer:
[tex]-y^{2}-4yi+4[/tex]
Step-by-step explanation:
we know that
[tex](a-b)^{2}=a^{2}-2ab+b^{2}[/tex]
we have
[tex](2-yi)^{2}[/tex]
substitute
[tex](2-yi)^{2}=(2)^{2}-2(2)(yi)+(yi)^{2}[/tex]
[tex](2-yi)^{2}=4-4yi+(y^{2})(i^{2})[/tex]
Remember that
[tex]i^{2}=-1[/tex]
substitute
[tex](2-yi)^{2}=4-4yi+(y^{2})(-1)[/tex]
[tex](2-yi)^{2}=4-4yi-y^{2}[/tex]
[tex](2-yi)^{2}=-y^{2}-4yi+4[/tex]
