x^2+2/5x-3/5=01 1 1 -3/5所以(x+1)(x-3/5)=0x=-1或x=3/5
x^2+2/5x=3/5x^2+2/5x+4/100=64/100x-1/5=±4/5x=1或-3/5
x²+2/5x-3/5=05x²+2x-3=0(x+1)(5x-3)=0x=-1或x=3/5
