We can solve this equation by completing the square. Notice that [tex]4*2=8[/tex] and [tex]4^{2}=16[/tex]. Therefore, we can turn [tex]y^{2}-8y+16=0[/tex] into [tex](y-4)^{2}=0[/tex]. y, in this equation, only has one real solution: 4. So your answer would be (B).
