Уравнение:
2x^2 + 6x + c = 0
По теореме Виета
x1 + x2 = -b/a = -6/2 = -3
x1*x2 = c/a = c/2
1/x1 + 1/x2 = (x1 + x2) / (x1*x2) = -3 / (c/2) = -6/c = 3
c = -6/3 = -2
См рисунок
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(2^2+2*2*10^3+10^2*3)*1/(12*10)^3=(4+4*10^3+10^6)/(12^3+3*12^2*10+3*12*10^2+10^3)=(1004004)/(10648)=94.2