韦达定理x1-x2的绝对值
x1+x2=-b/ax1x2=c/a
(x1+x2)^2=b^2/a^2
(x1-x2)^2=b^2/a^2-4c/a=b^2-4ac/a^2
绝对值x1-x2=√b^2-4ac/a的绝对值
即绝对值a分之√△
绛旓細闊﹁揪鍏紡鐨勮繍鐢▁1-x2鐨勭粷瀵瑰间竴鍏冧簩娆℃柟绋嬩腑浠ｈ〃涓や釜鏍瑰湪鏁拌酱涓婄殑璺濈锛屽洜涓猴紙X1+X2锛塣2-4X1*X2=X1^2+X2^2-2X1*X2=(x1-x2)^ 2鎵浠ュ氨鐢▅(x1-x2)|=(锛圶1+X2锛塣2-4X1*X2)^1/ 2 鍐嶇粨鍚堥煢杈惧畾鐞嗘潵姹傚嚭x1-x2鐨勭粷瀵瑰 ...
绛旓細缁濆鍊紉1-x2=鈭歜^2-4ac/a鐨勭粷瀵瑰 鍗崇粷瀵瑰糰鍒嗕箣鈭氣柍
绛旓細涓ょ偣闂磋窛绂诲叕寮忕敤闊﹁揪瀹氱悊鎺ㄥ杩囩▼锛歺1-x2鐨勭粷瀵瑰肩瓑浜庯紙x1-x2锛夌殑骞虫柟鍐嶅紑鏍瑰彿锛岋紙x1-x2锛夌殑骞虫柟绛変簬锛坸1-x1锛*锛坸1-x2锛-4x1x2=锛坆/a锛夛紙b/a锛-4c/a锛坸1+x2=b/a锛寈1/x2=c/a锛夛紝寰楀埌涓ょ偣闂寸殑璺濈涓烘牴鍙蜂笅锛坆*b-4ac锛夊啀闄や互a鐨勭粷瀵瑰笺傛敞锛氳鎺ㄥ箍褰㈠紡鐨勮瘉鏄庝竴鑸棤娉曟牴鎹眰鏍瑰叕...
绛旓細锛1锛夌敱闊﹁揪瀹氱悊寰楋細x1+x2=t, x1*x2=1, 鎵浠1-x2鐨勭粷瀵瑰肩瓑浜庢牴鍙蜂笅(锛坸1+x2锛塣2-4 x1*x2)=鏍瑰彿涓嬶紙t^2-4锛=2, 鎵浠ヨВ寰梩=姝ｈ礋2鏍瑰彿2 锛2锛 棰樼洰鐨勬剰鎬濆氨鏄g(x)鍑芥暟鐨勬渶灏忓兼瘮f(x)鍑芥暟鍦╗0,1]涓婄殑鏈灏忓煎ぇ鎴栫瓑浜庡嵆鍙 g(x)鍑芥暟鐨勬渶灏忓间负-1/3 瀵逛簬f(x)鍑芥暟锛...
绛旓細闊﹁揪瀹氱悊鏄痻1+x2=-b/a锛寈1*x2=c/a锛屽彲浠ュ厛姹傦紙x1-x2锛塣2锛岃岋紙x1-x2锛塣2=x1^2+x2^2-2*x2*x1=x1^2+x2^2+2*x2*x1-4*x2*x1=锛坸1+x2锛塣2-4*x2*x1锛岀劧鍚庡甫鍏ラ煢杈惧畾鐞嗗紑鏍瑰彿鍗冲彲姹傚嚭x1-x2銆
绛旓細瑙1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=卤锔扁垰(b²-4ac)锔/a銆傝В2锛氱敤鍏紡锛歺1锛寈2=銆-b卤鈭氾紙b²-4ac锛夈/2a銆傚垯锛歺1-x2=卤锔扁垰(b²-...
绛旓細鍋囪x1鍜寈2鍒嗗埆鏄柟绋媥²+4x-3=0鐨勪袱涓牴,璇峰埄鐢闊﹁揪瀹氱悊鐨勭浉鍏崇煡璇嗘眰(x1-x2)鐨勭粷瀵瑰銆... 鍋囪x1鍜寈2鍒嗗埆鏄柟绋媥²+4x-3=0鐨勪袱涓牴,璇峰埄鐢ㄩ煢杈惧畾鐞嗙殑鐩稿叧鐭ヨ瘑姹(x1-x2)鐨勭粷瀵瑰笺 灞曞紑 鎴戞潵绛 1涓洖绛 #鐑# OPPO FindX5绯诲垪鍏ㄦ柊涓婂競 ...
绛旓細x1,x2鏄柟绋嬬殑涓ゆ牴锛岀敱闊﹁揪瀹氱悊寰 x1+x2=-5/2锛寈1x2=-3/2 (x1-x2)²=x1²-2x1x2+x2²=(x1²+2x1x2+x2²)-4x1x2=(x1+x2)²-4x1x2 鍗(x1-x2)²=(-5/2)²-4脳(-3/2)=25/4+6=49/4 鎵浠x1-x2|=7/2 ...
绛旓細瑙ｏ細鐢闊﹁揪瀹氱悊锛X1+X2=-a/b=-2 X1X2=a/c=-3/2 鍥犱负缁濆鍊閲屼竴瀹氭槸姝ｇ殑锛屽紑鏂逛篃涓瀹氭槸姝ｇ殑锛屾墍浠ョ粷瀵瑰间笉绠″畠涔熸槸涓鏍风殑銆俋1-X1=锛圶1+X2)²-4X1X2鐨宸啀寮鏂=鏍瑰彿10
绛旓細鐩寸嚎鏂圭▼涓庢き鍦嗘柟绋嬭仈绔,寰楀埌鍏充簬x鐨勪竴鍏冧簩娆℃柟绋,鐢闊﹁揪瀹氱悊琛ㄧずx1+x2,x1脳x2,鐢(x1-x2)?=(x1+x2)?锛4x1脳x2,寰楀埌x1-x2鐨勭粷瀵瑰,寮﹂暱灏辨槸杩欎釜鍊济楁牴鍙1+k?,k鏄洿绾挎枩鐜.,3,
