Respuesta :

ghanami
hello : 
a point on the y-axis is : P( 0, y)
PA = PB  or  PA² = PB².... A(4 , -4)    B(1,1)
(4-0)²+(-4-y)² = (1-0)² + (1-y)²
16 +y² +8y +16 = 1 + 1 -2y +y²
10y = -30
y = -3