作业帮一道sat数学 if 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values ofif 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values of xy?A.xy=4B.0≤xy≤24C.-1≤xy≤11D.-1≤xy≤24E.-
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一道sat数学 if 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values ofif 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values of xy?A.xy=4B.0≤xy≤24C.-1≤xy≤11D.-1≤xy≤24E.-
一道sat数学 if 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values of
if 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values of xy?
A.xy=4
B.0≤xy≤24
C.-1≤xy≤11
D.-1≤xy≤24
E.-8≤xy≤24
我选了B不对 请跟我说下怎么做 很久以前学的都忘了
一道sat数学 if 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values ofif 0≤x≤8 and -1≤y≤3,which of the following gives the set of all possible values of xy?A.xy=4B.0≤xy≤24C.-1≤xy≤11D.-1≤xy≤24E.-
找极值点,两个都正数或负数,就找出绝对值最大的这里是（x,y）=（8,3）
所以xy最大为24
最小同理,（x,y）=（8,-1）,此时xy=-8
因此选e
这道题我也做过，这道题就是要小心 是个陷阱，要试数做啊...因为y跨了负数和正数的区间 所以要取极值点做出来
xy是x乘以y的意思 当x=1 Y=-1时，显然B就是错的
所以E