решение уравнение (7x+1) (x-3)+20(x-1)(x+1)=3(3x-2)²+13

(7x+1)(x-3)+20(x-1)(x+1) = 3(3x-2)²+13

7x²-20x-3+20x²-20 = 27x²-36x+12+13

27x²-20x-23=27x²-36x+25

36x-20x = 25+23

16x = 48

x = 3