1px solid black"> 1
2 |
x
2 +20x(0<x≤15)
(2)当y=200时,
解得x
1 =x
2 =20>15:inline-table;vertical-align;vertical-align,y有最大值;vertical-align
∴x=15时:middle" cellpadding="-1" cellspacing="-1"> |
1 |
2 |
x
2 +20x的图象是开口向下的抛物线:100%">
(1)根据题意得:y=x:1px solid black"> 1 |
2 |
×15
2 +20×15=187,最大面积为187,
∴当0<x≤15时,即-
x
2 +20x=200:middle" cellpadding="-1" cellspacing="-1">
40-x |
2 |
:middle" cellpadding="-1" cellspacing="-1">
赞11
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