<span>(3-5у)(1+2у) = 3 +6у -5у -10у^2= 3 + y -10y^2
</span>
-2; -4; -8;...
q = -4:(-2) = 2
S₇ = b₁(q⁷-1)/(q -1)
S₇ = -2*(2⁷-1)/(2 -1) = -2*127 = -254
1) 2х^2 + 17x = 0 2) 0.5x^2 + 9 = 0
x * (2x + 17) = 0 0.5x^2 = -9
x=0 или 2x + 17=0 0,5x^2= -9
2x = -17 x^2 = 9/0.5
x = -17/2 x^2 = -18
корней не существует