1) a^2=61
a=±sqrt61
sqrty^2=25
y=25
(x^2 + 3) ( x - 7) = 0
x^2 = - 3 ==> нет реш
x - 7 = 0 ==> x = 7
(3y - 1) (y^2 + 1) = 0
3y - 1 = 0 ==> 3y = 1 ==> y = 1/3
y^2 = - 1 ==> нет реш
(z - 1)^2 (z + 4) = 0
z - 1 = 0 ==> z = 1
z + 4 = 0 ==> z = - 4
(3t + 12) (t + 2)^2 = 0
3t + 12 = 0 ==> 3t = - 12 ==> t = - 4;
t + 2 = 0 ==> t = - 2