Решите 435 2) 2x*x-7x-4=0 4) 3x*x+2x-1=0 8) - 3x*x-x+4=0 436 2) 16x*x-8x+1=0 4) 36x*x+12x+1=0

435 2) 2 х^2 - 7 х - 4 = 0;

D = (-7) ^2 - 4 * 2 * (-4) = 49 + 32 = 81 = 9^2;

x1 = (7 - 9) / (2*2) = - 2/4 = - 1/2 = - 0,5;

x2 = (7 + 9) / (2*2) = 16/4 = 4.

Ответ: х1 = - 0,5, х2 = 4.

435 4) 3 х^2 + 2 х - 1 = 0;

D = 2^2 - 4 * 3 * ( - 1) = 4 + 12 = 16 = 4^2;

x1 = (-2 - 4) / 2*3 = - 6/6 = - 1;

x2 = (-2 + 4) / 2*3 = 2/6 = 1/3.

Ответ: х1 = - 1, х2 = 1/3.

435 8) - 3 х^2 - х + 4 = 0;

D = ( - 1) ^1 - 4 * ( - 3) * 4 = 1 + 48 = 49 = 7^2;

x1 = (1 - 7) / (2 * (-3)) = - 6/-6 = 1;

x2 = (1 + 7) / (2 * (-3)) = 8/-6 = - 1 2/6 = - 1 1/3.

Ответ: х1 = 1, х1 = - 1 1/3.

436 2) 16 х^2 - 8 х + 1 = 0;

D = (-8) ^2 - 4 * 16 * 1 = 64 - 64 = 0;

x = 8/2*16 = 8/32 = 1/4.

Ответ: х = 1/4.

436 4) 36 х^2 + 12 х + 1 = 0;

D = 12^2 - 4 * 36 * 1 = 144 - 144 = 0;

x = - 12/2 * 36 = - 12/72 = - 1/6.

Ответ: х = - 1/6.