4x² + 4x + 1 = 0

Bài 6.1:
a)4x² + 4x + 1=0
b)(x - 1)² + ( 3 - y )² =0
c)y² - 4x² + 4x - 1=0
d)x² - 4xy + 4y² + (x + 1)² =0