А. 3n-12n^2 = 3(n-4n^2)
15n+12= 3(5n+4)
б. 3n+1
в. 2n+21, делится когда 2n кратно 3, т.е. когда n=3k, k∈Z
9n^2 - 2n когда n кратно 3.
(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
1)5*5 ^2х)/4^2х=5*(5/4)^2
(5/4)^2x=(5/4)^2
2x=2
x=1