x1-x二的绝对值
你是想问x1-x二的绝对值是什么吗？x1-x二的绝对值是|x1-x2|=√(x1-x2)?=√[(x1+x2)?-4x1x2]=√(b?/a?-4c/a)=[√(b?-4ac)]/|a|。绝对值是指一个数在数轴上所对应点到原点的距离，用“||”来表示。绛旓細x1鈥x2鐨勭粷瀵瑰绛変簬鏍瑰彿涓嬶紙x1+x2锛夌殑骞虫柟鈥4x1x2鐒跺悗甯﹀叆鏃㈠彲銆
绛旓細鍥犱负x1锛x2鐨澶у皬鍏崇郴涓嶆槑纭紝鎵浠x1锛峹2|锛6 涓よ竟骞虫柟寰 x1²锛2x1x2+x2²锛36 (x1+x2)²锛4x1x2锛36 x1+x2涓巟1x2鍙牴鎹牴涓庣郴鏁扮殑鍏崇郴寰楀埌
绛旓細瑙:鈭祒1锛寈2婊¤冻缁濆鍊锛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
绛旓細闊﹁揪鍏紡鐨勮繍鐢 x1-x2鐨勭粷瀵瑰涓鍏冧簩娆℃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|x1-x2|=鈭氾紙x1+x2锛塣2-4x1x2 鐒跺悗澶ф鏄埄鐢ㄤ簩鍏冧竴娆℃柟绋嬫牴涓庣郴鏁扮殑鍏崇郴锛屽彲浠ュ緱 x1+x2=D x1x2=F 甯﹀叆鍗冲彲銆
绛旓細鍥犱负 锛坸1+x2锛夌殑骞虫柟-4x1x2=(x1鐨勫钩鏂+x2鐨骞虫柟+2x1x2)-4x1x2=x1鐨勫钩鏂+x2鐨勫钩鏂-2x1x2=(x1-x2)鐨勫钩鏂
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2x²-3x+1=锛x-1锛*锛2x-1锛=0锛屾墍浠₁=1 ,x₂=1/2,绛旀鏄5/4 璁板緱閲囩撼缁撹锛氱煶铚￠亣鍐峰嚌鍥猴紝鐕冪儳鏃朵骇鐢熺偔榛戯紝妫夌嚎鐐寲锛岀櫧鐑熺敱缁嗗皬鐨勭煶铚￠绮掓瀯鎴愶紝鏈夊彲鐕冩с傚疄楠岀粨璁猴細铚＄儧鍦ㄧ┖姘斾腑鑳藉鐕冪儳锛屽湪鐕冪儳杩囩▼涓拰杩囩▼鍚庤兘浜х敓璁稿鏂扮殑鐗╄川銆
绛旓細瑙ｏ細鐢遍煢杈惧畾鐞嗭紝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
绛旓細瀵逛簬ax2+bx+c锛x1-x2鐨勭粷瀵瑰绛変簬鏍瑰彿涓媥1-x2鐨勫钩鏂癸紝鑰寈1-x2鐨勫钩鏂瑰睍寮鏄痻12+x22-2x1x2,涔熷氨鏄(x1+x2)2-4x1x2,鑰寈1+x2鍜寈1x2鍙敤闊﹁揪瀹氱悊琛ㄧず锛屽寲绠鍚庡緱瑙
