<h3>OEF¸ñʽϽ»»¥Ê½Á·Ï°µÄÀý</h3>
ÒÔÏÂÊÇ¿ÉÀûÓÃ<b>´´½¨Á·Ï°</b>(createxo)´´½¨µÄ½»»¥Ê½Á·Ï°µÄÀý×Ó.
<ol>
<li> <hr style="width:50%"/>
<b>2άÏòÁ¿µÄ³¤¶È</b>, Æ½ÃæÄÚÏòÁ¿µÄ³¤¶ÈµÄ¼òµ¥¼ÆËã.
ÏÂÃæÊÇÕâ¸öÁ·Ï°µÄÍêÕûÔ´´úÂë.
<pre>
\title{2άÏòÁ¿µÄ·¶Êý}
\language{cn}
\computeanswer{no}
\format{html}
\integer{x=random(-10..10)}
\integer{y=random(-10..10)}
\real
{norm
=sqrt((\x
)^
2+(\y
)^
2)}
\statement{R<sup>2</sup>ÖÐÏòÁ¿(\x,\y)µÄ³¤¶ÈÊÇʲô?}
\hint
{ÏòÁ¿
(x
,y
)µÄ³¤¶ÈµÈÓÚ
sqrt(x^
2+y^
2).}
\answer{³¤¶È}{\norm}
</pre>
ÔÚÕâ¸öÁ·Ï°ÖÐ, ¶¨ÒåÁËÁ½¸öËæ»úÕûÊýxÓëy, ËüÃÇÊÇÏòÁ¿µÄ×ø±ê.
µÚÈý¸ö²ÎÊýÊÇʵÊý, Óɳ¤¶È¹«Ê½ËùÈ·¶¨. ±¾Á·Ï°²ÉÈ¡×ÔÓɸñʽµÄ»Ø´ð,
ÆäÃû³ÆÊÇ``³¤¶È'', ÆäÕýÈ·»Ø´ðÓ¦¸ÃÊǵÚÈý¸ö²ÎÊý``·¶Êý''µÄÖµ.
±¾Á·Ï°×¼±¸ÁËÒ»¸öÌáʾ, Ëü¸´Ï°Á˳¤¶È¹«Ê½. <p>
Äã¿ÉÒÔ
!set parm=oef_answercnt=1&oef_choicecnt=0&oef_title=2άÏòÁ¿µÄ·¶Êý&oef_format=html&oef_computeanswer=no&level=2&oef_parms=%5Cinteger%7Bx%3Drandom%28-10..10%29%7D%0D%0A%5Cinteger%7By%3Drandom%28-10..10%29%7D%0D%0A%5Creal%7Bnorm%3Dsqrt%28%28%5Cx%29%5E2%2B%28%5Cy%29%5E2%29%7D&oef_statement=R%3Csup%3E2%3C%2Fsup%3EÖÐÏòÁ¿%28%5Cx%2C%5Cy%29µÄ³¤¶ÈÊÇʲô&ansprompt1=³¤¶È&ansgood1=%5Cnorm&oef_hint=ÏòÁ¿%28x%2Cy%29µÄ³¤¶ÈfµÈÓÚ%0D%0Asqrt%28x%5E2%2By%5E2%29.&oef_solution= $
!href cmd=reply&mode=guided&$parm ½«´ËÀý×Ó¶ÁÈë²Ëµ¥
ÒÔ²âÊÔËü. (ÄãÒ²¿ÉÒÔÔÚÔ´ÂëģʽϰÑÔ´´úÂë¸´ÖÆÈë²Ëµ¥.)
<li> <hr style="width:50%"/>
<b>2x2¾ØÕóµÄ¼£</b>, ¼ÆËã¾ØÕóµÄ¼£. ÏÂÃæÊÇÁ·Ï°µÄÍêÕûÔ´´úÂë.
<pre>
\title{2x2¾ØÕóµÄ¼£}
\language{cn}
\computeanswer{yes}
\format{html}
\integer{trace=(\a)+(\d)}
\statement{¼ÆËãÒÔϾØÕóµÄ¼£<center>
\(\pmatrix{\a&\b\cr \c&\d}).</center>}
\answer{¼£}{\trace}
</pre> <p>
ÎÒÃÇÊ×Ïȶ¨ÒåÁËÕûÊý``
range''ÓÃ×÷¾ØÕóÔªËØa
,b
,c
,dµÄËæ»úÊýÖµµÄ½ç
.
¾ØÕóµÄ¼£µ±È»¶¨ÒåΪ¶Ô½ÇÏßÔªËØÖ®ºÍ. Çë×¢ÒⶨÒå
<span class="tt">trace=(\a)+(\d)</span>: ÆäÖÐÀ¨ºÅ¶ÔÊDZØÒªµÄ, ÒòÎªÌæ»»Êǰ´×ÖÃæÒâÒåÖ´ÐеÄ.
Èç¹ûÄ㶨Òå<span class="tt">trace=\a+\d</span>, ¶øÇÒaºÍb·Ö±ðȡֵ3Óë-15,
Ä㽫µÃµ½<span class="tt">trace=3+-15</span>, ÕâÊÇÒ»¸ö´íÎóµÄÊýѧ±í´ïʽ. <p>
Çë×¢ÒâÔÚÕâ¸öÁ·Ï°ÀïÔÊÐíδ¾¼ÆËãµÄ»Ø´ð
(ÀýÈç2+15»ò3*105). <p>
Äã¿ÉÒÔ
!set parm=oef_answercnt=1&oef_choicecnt=0&oef_title=2x2¾ØÕóµÄ¼£&oef_format=html&oef_computeanswer=yes&level=2&oef_parms=%5Cinteger%7Brange%3D20%7D%0D%0A%5Cinteger%7Ba%3Drandom%28-%5Crange..%5Crange%29%7D%0D%0A%5Cinteger%7Bb%3Drandom%28-%5Crange..%5Crange%29%7D%0D%0A%5Cinteger%7Bc%3Drandom%28-%5Crange..%5Crange%29%7D%0D%0A%5Cinteger%7Bd%3Drandom%28-%5Crange..%5Crange%29%7D%0D%0A%5Cinteger%7Btrace%3D%28%5Ca%29%2B%28%5Cd%29%7D&oef_statement=¼ÆËãÒÔϾØÕóµÄ¼£%3Ccenter%3E%0D%0A%5C%28%5Cpmatrix%7B%5Ca%26%5Cb%5Ccr %5Cc%26%5Cd%7D%29.%3C%2Fcenter%3E&ansprompt1=¼£&ansgood1=%5Ctrace&oef_hint= &oef_solution= $
!href cmd=reply&mode=guided&$parm ½«´ËÀý×Ó¶ÁÈë²Ëµ¥
ÒÔ²âÊÔËü. (ÄãÒ²¿ÉÒÔÔÚÔ´ÂëģʽÖаÑÔ´´úÂë¸´ÖÆÈë²Ëµ¥.)
</ol>