По моему подобие треугольников.
X^2 - x/6 - 2 = 0
D = (-1/6)^2 - 4*1*(-2) = 1/36 + 8 = 289/36
x1 = (1/6 + 17/6)/2 = 18/12 = 3/2,
x2 = (1/6 - 17/6)/2 = -8/6 = -4/3.
4*(1 1/4 *5/8)=4*(5/4 *5/8)=4*25/32=25/8=3 1/8
1/(3 - lgx) + 2/(lgx - 1) = 3;
(lgx - 1 + 6 - 2lgx)/((3 - lgx)(lgx - 1)) = 3;
-lgx + 5 = 3(3 - lgx) (lgx - 1);
-lgx + 5 = 9lgx - 9 - 3lg^2x + 3lgx;
-3lg^2x + 13lgx - 14 = 0;
lgx = a;
-3a^2 + 13a - 14 = 0;
D = 169 - 168 = 1;
a = - 2, a = 14/6 = 7/3;
lgx = -2 => 10^-2 = x, x = 1/100 = 0,01;
lgx = 7/3 => x = 10^(7/3).
Ответ: 0,01; 10^(7/3).
<span>(9-b)^2-b(b-7)=b^2-18b+81-b^2+7b=81-11b
81-11*(-0.8)=81+8.8=89.8</span>