抛物线y=1/2x²-2x+3/2与x轴交与AB两点,则AB的长是

问题描述:

抛物线y=1/2x²-2x+3/2与x轴交与AB两点,则AB的长是

y=1/2x²-2x+3/2与x轴交于(X1,0)和(x2,0).则xi+x2=4,x1x2=3..所以|x2-x1|=根{(x1+x2)²-4x1x2}= 根 (16-12)=2,所以AB=2.