Это сумма членов арифметической прогрессии:
d = 6
n = 324/6 = 54
a = 6
Sn = (2a+(n-1)*d)/2*n = (2*6 + 53*6)/2*54 = 8910
1,2аbc*5a = 6a²bc
коэффициент - 6
{ 2x² + xy = 40
{ 3x - y = 10
{ y = 3x - 10
{ 2x² + x(3x - 10) = 40
5x² - 10x - 40 = 0
x² - 2x - 8 = 0 D = b²-4ac = 4+32 = 36
x₁ = (-b+√D)/2a = (2+6):2 = 4 y₁ = 3x - 10 = 2
x₂ = (-b-√D)/2a = (2-6):2 = -2 y₂ = 3x - 10 = -16
Ответ: {4; 2}; {-2; -16}