Jawapan

2015-10-22T02:24:47+08:00
Jawapan:
       = (y-1) (y-1)
       = y² -y -y +1
       = y² -2y +1
2015-10-22T11:39:36+08:00
Y² - 2y + 1 = (y - 1)²
                 = (y-1)(y-1)