数学高手请进抛物线圆形一次函数.3问.
3个回答

(1)解析:∵函数y=f(x)=-√3(x+m)(x-3m)/(3m)∴f(0)=-√3(m)(-3m)/(3m)=√3m==>D(0,√3m)∵f(x)图像与Y轴正半轴交于D∴m>0令f(x)=√3(x+m)(x-3m)/(3m)=0==>(x+m)(x-3m)=0∴A(-m,0),B(3m,0)(2)解析:∵E(-3,0)直线ED斜率为:k=tan∠DEO=√3/3m方程:y=√3/3m(x+3)F(x)对称轴x=mf(m)=-√3(m+m)(m-3m)/(3m)=4m√3/3==>M(m,4m√3/3)将M代入ED方程4m√3/3=√3/3m(m+3)==>m=1∴当m=1时,M点在直线ED上A(-1,0),B(3,0),C(1,0),D(0, √3)|CD|=2,C到ED的距离d=2∴ED是圆C的切线,切点为D(3)解析:S(⊿AED)=1/2|EA|*|OD|=1/2(3-m)(√3m)=3√3/2m-√3/2m^2