Решите уравнения:

5y^2+20y+20=0

(x^2+3) (x-7) = 0

(3y-1) (y^2+1) = 0

(z-1) ^2 (z+4) = 0

(3t+12) (t+2) ^2=0

(y-3) ^2-4 (3-y) = 0

5y^2+20y+20=0

D=b^2-4ac=20^2-4*5*20=400-400=0; корень из D=0

x = (-b+-корень из D) / 2a

x = (-20+-0) / 2*5=-20/10=-2

(x^2+3) (x-7) = 0

x^3-7x^2 + 3x - 21=0

x^2 (x-7) + 3 (x-7) = 0

(x^2+3) (x-7) = 0

x^2+3=0 или x-7=0

x^2=-3 x=7

решений нет

(3y-1) (y^2+1) = 0

3y^3-y^2+3y-1=0

y^2 (3y-1) + 1 (3y-1) = 0

(y^2+1) (3y-1) = 0

y^2+1=0 или 3y-1=0

y^2=-1 3y=1

решений нет y=1/3

5y^2+20y+20=0

y^2+4y+4=0

y=-2

(x^2+3) (x-7) = 0

x^2+3=0 x-7=0

x^2=-3 - (нет решений) x=7

(3y-1) (y^2+1) = 0

3y-1=0 y^2+1=0

3y=1 y^2=-1 - (нет решений)

y=1/3

(z-1) ^2 (z+4) = 0

(z-1) ^2=0 z+4=0

z^2-2z+1=0 z2=-4

z1=1

(3t+12) (t+2) ^2=0

3t+12=0 (t+2) ^2=0

3t=-12 t^2+4t+4=0

t1=-4 t2=-2

(y-3) ^2-4 (3-y) = 0

y^2-6y+9-12+4y=0

y^2-2y-3=0

y1=3 y2=-1