0.3х(х+13)-2х(0.9-0.2х)=0
0.3x^2+3.9x-1.8x+0.4x^2=0
0.7x^2+2.1x=0
x(0.7x+2.1)=0
x=0 0.7x+2.1=0
0.7x=-2.1
x=-3
0.3х(х+13)-2х(0.9-0.2х)=0
0.3x^2+3.9x-1.8x+0.4x^2=0
0.7x^2+2.1x=0
x(0.7x+2.1)=0
x=0 0.7x+2.1=0
0.7x=-2.1
x=-3