如图,直线y=kx(k<0)与双曲线y=−2x交于A(x1,y1),B(x2,y2)两点,则3x1y2-8x2y1的值为( ) A.-5 B.-10 C.5 D.10
问题描述:
如图,直线y=kx(k<0)与双曲线y=−
交于A(x1,y1),B(x2,y2)两点,则3x1y2-8x2y1的值为( )2 x
A. -5
B. -10
C. 5
D. 10
答
∵A(x1,y1),B(x2,y2)双曲线y=−2x上的点,∴x1y1=-2,x2y2=-2,∵直线y=kx(k<0)与双曲线y=−2x交于A(x1,y1),B(x2,y2)两点,∴x1=-x2,y1=-y2,∴x1y2=-x1y1,x2y1=-x2y2,∴3x1y2-8x2y1=-3x1y1+8...