已知方程组{(2K-1)X-(K+1)Y=3K,(4K-1)X-(3K+1)Y=5K+4.求满足XY>-1的K的取值范围
问题描述:
已知方程组{(2K-1)X-(K+1)Y=3K,(4K-1)X-(3K+1)Y=5K+4.求满足XY>-1的K的取值范围
答
因为方程组(2K-1)X-(K+1)Y=3K和(4K-1)X-(3K+1)Y=5K+4.所以(4K-1)(2K-1)X-(4K-1)(K+1)Y=3K(4K-1)和(2K-1)(4K-1)X-(2K-1)(3K+1)Y=(2K-1)(5K+4).两式相减解得Y=(2k^2-6k+4)/(2k^2-4k)=(k^2-3k+2)/(k^2-2k)=(k...