[질문] 1차,2차,3차,4차,5차,6차방정식의해를구하는방법은무엇인가요???

예를들어일차방정식2x-6=0의해는x=3한개이고,이차방정식-3x²+2x+5=0의해는x=-1,5/3으로두개입니다.그리고3차방정식x³+2x²-x-2=0은x=1,x=-1,x=-2의3개입니다4차방