急求！！为什么x1-x2的绝对值=根号下（x1+x2）的平方-4x1x2主要是根号下的部分具体是怎么来的，谢谢啦！ x1-x2的绝对值=根号下（x1+x2）的平方-4x1x2的...
\u4e3a\u4ec0\u4e48x1-x2\u7684\u7edd\u5bf9\u503c=\u6839\u53f7\u4e0b\uff08x1+x2\uff09\u7684\u5e73\u65b9-4x1x2,\u5177\u4f53\u600e\u4e48\u63a8\u51fa\u6765\u7684\u554a\uff0c\u8c22\u8c22\u5566\u56e0\u4e3a
\uff08x1+x2\uff09\u7684\u5e73\u65b9-4x1x2=(x1\u7684\u5e73\u65b9+x2\u7684\u5e73\u65b9+2x1x2)-4x1x2=x1\u7684\u5e73\u65b9+x2\u7684\u5e73\u65b9-2x1x2=(x1-x2)\u7684\u5e73\u65b9
\u8fd9\u5c5e\u4e8e\u97e6\u8fbe\u5b9a\u7406\u7684\u62d3\u5c55\u3002
\u9996\u5148\u53ef\u4ee5\u7528\u4e8e\u6c42|x1-x2|
\u5176\u6b21 \u5728\u89e3\u6790\u51e0\u4f55\u4e2d \u5e38\u5e94\u7528
\u5c24\u5176\u662f\u5728\u76f4\u7ebf\u548c\u66f2\u7ebf\u76f8\u4ea4\u6c42\u4ea4\u70b9\u95f4\u7ebf\u6bb5\u957f\u5ea6\u65f6\u3002
绛旓細|x1-x2|=鈭(x1-x2)^2=鈭(x1^2-2x1x2+x2^2)=鈭(x1^2+2x1x2+x2^2-4x1x2)=鈭歔(x1+x2)^2-4x1x2]=鈭歔(-b/a)^2-4c/a]=鈭歔(b^2-4ac)/a^2]=鈭氣柍/|a|
绛旓細(x1涓x2)鐨勭粷瀵鍊 鎴戞潵绛 1涓洖绛 #鐑# 浣犲彂鏈嬪弸鍦堜細浣跨敤閮ㄥ垎浜哄彲瑙佸姛鑳藉悧? 鍖垮悕鐢ㄦ埛 2014-07-16 灞曞紑鍏ㄩ儴 鏇村杩介棶杩界瓟 杩界瓟 鑲畾瀵 璇烽噰绾 宸茶禐杩 宸茶俯杩< 浣犲杩欎釜鍥炵瓟鐨勮瘎浠锋槸? 璇勮 鏀惰捣 涓轰綘鎺ㄨ崘: 鐗瑰埆鎺ㄨ崘 鎽搁奔涓轰粈涔涔熶細鐒﹁檻? 涓鍒嗛挓鐨凪BTI鎬ф牸娴嬭瘯闈犺氨鍚? 涓婃捣涓轰粈涔堟湁...
绛旓細鎬ユ眰!!涓轰粈涔坸1-x2鐨勭粷瀵鍊=鏍瑰彿涓(x1+x2)鐨勫钩鏂-4x1x2涓昏鏄牴鍙蜂笅鐨勯儴鍒嗗叿浣撴槸鎬庝箞鏉ョ殑,璋㈣阿鍟!1涓洖绛 #鐑# 鑱屽満涓婂彈濮斿眻瑕佷笉瑕佷负鑷繁瑙ｉ噴?feng123h0 2013-12-21 路 TA鑾峰緱瓒呰繃6125涓禐 鐭ラ亾澶ф湁鍙负绛斾富 鍥炵瓟閲:2849 閲囩撼鐜:100% 甯姪鐨勪汉:2159涓 鎴戜篃鍘荤瓟棰樿闂釜浜洪〉 鍏虫敞 ...
绛旓細鍥犱负sin鍥惧儚鏄寰嬪嚱鏁板摝锛屽浘鍍忎粎渚涘弬鑰冿紝涓嶆槸鏈綋鍏蜂綋鍥惧儚鍠
绛旓細鐢诲浘銆傘傘備綘鎯宠薄鎶婂嚱鏁板浘鍍忓悜涓嬪钩绉讳竴涓崟浣嶉暱搴︼紝x1鍜x2灏遍兘鍦▁杞翠笂浜嗭紝鍒氬ソ浜屽垎涔嬩笁涓懆鏈
绛旓細杩欎釜鏄彲浠ヤ綔涓轰竴涓畾鐞嗚涓涓嬬殑锛岃璇佹槑璧锋潵涔熷緢绠鍗曘傛妸鍥涜竟褰㈢湅鎴愪袱涓笁瑙掑舰APQ鍜孊PQ锛屽簳杈归暱PQ=6锛屽洜涓篜Q鏄瀭鐩翠簬x杞寸殑锛屾墍浠ヤ袱涓笁瑙掑舰鐨勯珮鍒嗗埆涓篨1鍜孹2鍒癙Q鐨勮窛绂伙紝璁句负H1鍜孒2锛屽洓杈瑰舰闈㈢Н=1/2*PQ*H1+1/2*PQ*H2=1/2*PQ*(H1+H2)=1/2*PQ*|X1-X2| ...
绛旓細棣栧厛锛岀敤鍥犲紡鍒嗚В鏄彲浠ョ殑銆傝岀敤骞虫柟锛屾槸涓轰簡鍒╃敤闊﹁揪瀹氱悊 涓鑸竴鍏冧簩娆℃柟绋媋x^2+bx+c=0 涓ゆ牴x1+x2= -b/a x1x2=c/a x1-x2 鐨勭粷瀵鍊肩殑骞虫柟 =x1^2-2x1x2+x2^2 =(x1+x2)^2-4x1x2 =(b^2-4ac)/a 鍐嶅紑鏂瑰緱鍒 x1-x2 鐨勭粷瀵瑰 杩欐牱涓嶇敤姹傛牴鐩存帴绠楀嚭 x1-x2 鐨勭粷瀵瑰硷紝瀵逛簬...
绛旓細瑙:鈭祒1锛寈2婊¤冻缁濆鍊硷紙X1-X2锛=鈭5,鈭(x1-x2)^2=5,鈭祒1.x2骞冲潎鏁版槸x=(x1+x2)/2.鈭存柟宸=[(x1-x)^2+(x2-x)^2]/2 =[(x1-x2)^2/4+(x2-x1)^2/4]/2 =[2(x1-x2)^2/4]/2 =(x1-x2)^2/4 =5/4
绛旓細x1➖x2鐨勭粷瀵鍊兼槸浠涔 =鈭(x1-x2)²=鈭歔(x1+x2)²-4x1x2]=鈭(b²-4ac) /|a|
绛旓細x1鍑x2鐨鍏紡鏄細x1-x2=卤锔扁垰(b²-4ac)锔/a銆傝涓鍏冧簩娆℃柟绋媋x²+bx+c=0鐨勪袱涓牴涓簒1锛寈2銆傦紙a锛0锛夎В1锛氱敱闊﹁揪瀹氱悊锛歺1+x2=-b/a锛寈1x2=c/a銆傦紙x1-x2锛²=锛坸1+x2锛²-4x1x2=锛-b/a锛²-4c/a=锛坆²-4ac锛/a²銆倄1-x2=...
