Question

已知抛物线y=ax2=bx=c(a

Answer 1

点C的坐标为(0,c),设M,N的坐标为(x1,0),(x2,0),则

(c-0)^2+(0-x1)^2+(c-0)^2+(0-x2)^2=(x1-x2)^2

2c^2+x1^2+x^2=x1^2+x2^2-2x1x2

即x1x2=-c^2

又x1x2=c/a

所以a=-1/c