7x+x (x-7) = (2x+5) (5-2x)
7x+x (x-7) = (2x+5) (5-2x) 7x+x²-7x = (5+2x) (5-2x) 7x+x²-7x = 25-4x² x² +4x²-25=0 5x²-25=0 5(x²-5)=0 5≠0, значит х²-5=0 х²=5 х1=√5 х2=-√5