Решите уравнения 1) x(x-8)= 0 2) z^2-3z=0 3)-2x^2+13x =0 4)(y-5)(y+11)=0 5)

1) x * (x - 8) = 0;

х = 0;

x - 8 = 0;

х = 8.

2) z^2 - 3z = 0;

z * (z - 3) = 0;

z = 0;

z - 3 = 0;

z = 3.

3) -2x^2 + 13x = 0;

x * (-2x + 13) = 0;

x = 0;

-2x + 13 = 0;

-2x = -13;

x = - 13 : (-2);

x = 6,5.

4) (y - 5) * (y + 11) = 0;

y^2 + 11y - 5y - 55 = 0;

y^2 + 6y - 55 = 0;

D = b^2 - 4ac = 36 - 4 * 1 * (-55) = 36 + 220 = 256;

D = 256 = 16.

x1 = (-b + D)/2a = (-6 + 16)/2 = 10/2 = 5.

x2 = (-b - D)/2a = (-6 - 16)/2 = -22/2 = -11.

5) t^2 + 12t = 0;

t * (t + 12) = 0;

t = 0;

t + 12 = 0;

t = -12.

6) -x^2 + 25 = 0;

-x^2 = -25;

x^2 = 25;

x = 25;

x = 5.