З) 81-x^2=0 и) 2y^2-2=0 к) 16-4y^2=0 л) x^3-4x=0 м) t^2-t^4=0 н) x^2+4x+4=0 o) 4z^2-4z+1=0

З). 81 - x² = 0;

x² = 81; x = 9; x' = - 9;

и). 2y² - 2 = 0; 2 (y² - 1) = 0;

y² - 1 = 0;

y² = 1; y = 1; y' = - 1;

к). 16 - 4 y² = 0; 4 (4 - y²) = 0;

4 - y² = 0;

y² = 4; y = 2; y' = - 2;

л). x³ - 4 x = 0; x (x² - 4) = 0;

x = 0;

x² - 4 = 0; x² = 4;

x' = 2; x'' = - 2;

м). t² - t^4 = 0; t² (1 - t²) = 0;

t = 0;

1 - t² = 0; t² = 1;

t' = 1; t'' = - 1;

н). x² + 4 x + 4 = 0;

(x + 2) ² = 0;

x = - 2;

o). 4 z² - 4 z + 1 = 0;

(2 z - 1) ² = 0;

2 z - 1 = 0; 2 z = 1;

z = 1/2.