已知多项式kx^2-6xy-8y^2可分解为2(mx+y)(x-4y),求k和m的值
问题描述：
已知多项式kx^2-6xy-8y^2可分解为2(mx+y)(x-4y),求k和m的值
答
因为2(mx+y)(x-4y)=2（mx^2-4mxy+xy-4y^2)=2mx^2+(2-8m)xy-8y^2
又因为kx^2-6xy-8y^2=2(mx+y)(x-4y)，
即 kx^2-6xy-8y^2=2mx^2+(2-8m)xy-8y^2
所以
k=2m,
-6=2-8m,
所以 m=1,k=2m=2
答
已知多项式kx^2-6xy-8y^2可分解为2(mx+y)(x-4y),求k和m的值因为2(mx+y)(x-4y)=2（mx^2-4mxy+xy-4y^2)=2mx^2+(2-8m)xy-8y^2 又因为kx^2-6xy-8y^2=2(mx+y)(x-4y),即 kx^2-6xy-8y^2=2mx^2+(2-8m)xy-8y^2 所以 k=2m,-6=2...