1.Найдите восьмой член геометрической прогрессии 3,2 ;1,6 ;0,8;... 2.Сократите дробь (2-4х)^2/4х^2-1

1.

3,2; 1,6; 0,8;...

b1 = 3,2;

b2 = 1,6;

bn = b1 * q^(n - 1);

b8 = b1 * q^(8 - 1) = b1 * q^7;

q = b2/b1;

q = 1,6/3,2;

q = 0,5;

b8 = 3,2 * (0,5)^7 = 0,025.

2.

(2 - 4х)^2/(4х^2 - 1) = (4 - 16x + 16x^2)/(2x - 1)(2x - 1) = (16(x - 1/2)(x - 1/2))/(2x - 1)(2x - 1) = (16(x - 1/2)(x - 1/2))/(2(x - 1/2)2(x - 1/2)) = 4;

3.

 b^5 * b^11 = 8;

b1 * q^4 * b1*q^10 = 8;

b1^2 * q^14 = 8;

b8 = b1 * q^7;

b1 * q^7 * (b1 * q^7) = 8;

b8 * b8 = 8;

b8 = +- 8.