=(y²-9)(y²+9)-(4y^4-4y³+y²)-19=y^4-81-4y^4+4y³-y²-19=-3y^4+4y³-y²-100
(3,6 - 4 2/9) * 2 4/7 = - 28/45
1) 3,6 - 4 2/9 = 36/10 - 38/9 = 324/90 - 380/90 = - 56/90 = - 28/45
________________________________
100% + 30% = 130% = 1,3
100% + 20% = 120% = 1,2
1,3 * 1,2 = 1,56 * 100 = 156 станет произведение
156% - 100% = = 56% настолько измениться произведение
b1 = 512; bn = 1; Sn = 1023;
Sn = (bn · q - b1)/(q - 1)
1023 = (q - 512)/(q - 1)
1023q - 1023 = q - 512
1022q = 511
q = 1/2
bn = b1 · q^(n - 1) 1 = 512 · (1/2)^(n -1) 1/512 = 1/2^(n - 1)
1/2^9 = 1/2^(n - 1)
9 = n - 1
n = 10
Ответ: n = 10; q = 1/2
2(х1+х2) - 5х1х2 = 24 - 95 = -69