当x+y=2/31,xy= -5/51时,求代数式6x+5xy+6xy的值.
问题描述:
当x+y=2/31,xy= -5/51时,求代数式6x+5xy+6xy的值.
答
x+y=2/31,是2分之31吧?
xy= -5/51时,
6x+5xy+6y
=6(x+y)+5xy
=6×31/2+5×(-51/5)
=93-51
=42