题目有误,犹似:
{[-b+根号(b²-4ac)]/2a}*{[-b-根号(b²-4ac)]/2a }
={[-b+√(b²-4ac)]/2a}*{[-b-√(b²-4ac)]/2a}
=[-b+√(b²-4ac)*[-b-√(b²-4ac)]/4a²
={(-b)²-[√(b²-4ac)]²}/4a²
=[b²-(b²-4ac)]/4a²
=4ac/4a²
=c/a
题目有误,犹似:
{[-b+根号(b²-4ac)]/2a}*{[-b-根号(b²-4ac)]/2a }
={[-b+√(b²-4ac)]/2a}*{[-b-√(b²-4ac)]/2a}
=[-b+√(b²-4ac)*[-b-√(b²-4ac)]/4a²
={(-b)²-[√(b²-4ac)]²}/4a²
=[b²-(b²-4ac)]/4a²
=4ac/4a²
=c/a