若3A减6B的值与x的取值无关,求y的值，并求出3A减6B的值
\u56fe\u7247\u662f\u5df2\u77e5\u7684\uff0c\u9898\u662f\uff1a\u82e53a\u52a06b\u7684\u503c\u4e0ex\u7684\u53d6\u503c\u65e0\u5173\uff0c\u6c42y\u7684\u503c
\u6ce8\u610f\u6df1\u523b\u7406\u89e3\u201c\u4e0eX\u65e0\u5173\u201d\u7684\u542b\u4e49\u3002
x(15y-6)-9,\u4e0eX\u65e0\u5173\uff0c\u610f\u5473\u7740\u65e0\u8bbax\u53d6\u4f55\u503c\uff0c\u8fd9\u4e2a\u5f0f\u5b50\u7684\u503c\u90fd\u4e0d\u53d8\u3002
\u6240\u4ee5\uff0c\u5f53\u4e14\u4ec5\u5f53\u62ec\u53f7\u5185\u7684\u4e3a\u96f6\uff0c\u624d\u80fd\u8fbe\u5230\u4e0a\u8ff0\u6548\u679c\u3002
也就是说3xy加6x=0
即y=-2.所以3A-6B=6y+3=-9
绛旓細娉ㄦ剰娣卞埢鐞嗚В鈥涓嶺鏃犲叧鈥濈殑鍚箟.x(15y-6)-9,涓嶺鏃犲叧,鎰忓懗鐫鏃犺x鍙栦綍鍊,杩欎釜寮忓瓙鐨勫閮戒笉鍙.鎵浠,褰撲笖浠呭綋鎷彿鍐呯殑涓洪浂,鎵嶈兘杈惧埌涓婅堪鏁堟灉.
绛旓細宸茬煡A=2X鐨勫钩鏂+3XY-2X-1,B=-X鐨勫钩鏂+XY-1,鑻3A+6B鐨勫间笌X鐨勫彇鍊兼棤鍏,姹 Y鐨勫,瑕佽繃绋嬨... Y鐨勫,瑕佽繃绋嬨 灞曞紑 鎴戞潵绛 1涓洖绛 #鐑# 鍙箰鏍,鏄粈涔堟爲?c6g 2013-12-09 路 TA鑾峰緱瓒呰繃8609涓禐 鐭ラ亾灏忔湁寤烘爲绛斾富 鍥炵瓟閲:4654 閲囩撼鐜:100% 甯姪鐨勪汉:481涓 鎴戜篃鍘荤瓟棰...
绛旓細瑙ｏ細锛1锛3A+6B=3锛2x2+3xy-2x-1锛+6锛-x2+xy-1锛=6x2+9xy-6x-3-6x2+6xy-6=15xy-6x-9锛涳紙2锛夊師寮=15xy-6x-9=锛15y-6锛墄-9 瑕佷娇鍘熷紡鐨勫间笌x鏃犲叧锛屽垯15y-6=0锛岃В寰楋細y=25锛
绛旓細缁撴灉涓猴細2/5銆傝В棰樿繃绋嬶細
绛旓細宸茬煡A=2x²+3xy-2x-1锛孊=-x²+xy-1锛屼笖3A+6B鐨勫间笌x鏃犲叧锛屾眰y鐨勫硷紵瑙ｏ細鍙緱锛3A+6B =3(2x²+3xy-2x-1)+6(-x²+xy-1)=6x²+9xy-6x-3-6x²+6xy-6 =15xy-6x-9 =(15y-6)x-9 鐢变簬涓婂紡涓巟鐨勫彇鍊兼棤鍏锛岃〃鏄巟鐨勭郴鏁板簲璇ヤ负0锛屽嵆锛15y-...
绛旓細3A+6B =3(-2x+3ax+2x²-1)+6(-x²-1+ax)=-6x+9ax+6x²-3-6x²-6+6ax =(15a-6)x-9 鍊间笌x鐨勫彇鍊兼棤鍏鍒檟绯绘暟涓 鎵浠15a-6=0 a=2/5
绛旓細3a+6b =3锛2X^2+3XY-2X-1锛+6锛-X^2+XY-1锛=6x^2+9xy-6x-3-6x^2+6xy-6 =15xy-6x-9 =x(15y-6)-9 涓巟鏃犲叧 鍒檟鍓嶇郴鏁 =0 15y-6=0 y=2/5
绛旓細灏咥鍜B鐨勫浠ｅ叆3A+6B涓紝璁╁惈鏈墆鐨勯儴鍒+鍚玿涓嶅惈y鐨勯儴鍒=0锛屾秷鎺墄姹傚嚭y灏辫浜嗐傚鏋淎=2x²+3xy-2x-1锛孊=-x²+xy-1锛屽垯3A+6B=15xy-6x-9锛涘洜涓烘鍊艰窡x鏃犲叧锛屾墍浠ヤ护15xy-6x=0锛屽彲瑙ｅ緱y=0.4
绛旓細瑙ｉ鎬濊矾:涓や唬鏁板紡鍖栫畝鍚庢墍鏈夊惈x鐨勫紡瀛愮郴鏁扮瓑浜0(鎶妝褰撲綔鏄痻鐨勭郴鏁)灏辫杩欎箞澶,鑷繁鍐嶆濊冧竴涓嬪惂.3A+6B =3(2X²+3XY-2X-1)+6(-X²+XY-1)=6x^2+9xy-6x-3-6x^2+6xy-6 =15xy-6x-9 =(15y-6)x-9 鍊间笌x鐨勫彇鍊兼棤鍏璇存槑x鍓嶇殑绯绘暟涓0锛屽嵆 (15y-6锛=0 y=6/15=2...
绛旓細a=2x^2+3xy-1锛宐=-x^2+xy-1锛屸斺斻3a+6b=(6x^2+9xy-3)+(-6x^2+6xy-6)=15xy-9锛涓巟鐨勫彇鍊兼棤鍏锛屸斺斻15y=0锛屸斺斻媦=0銆
