十字相乘法怎么用?
\u600e\u6837\u7528\u5341\u5b57\u76f8\u4e58\u6cd5ax2+bx+c \u8fd9\u662f\u4e00\u822c\u5f62\u5f0f\uff08a\u3001b\u3001c\u90fd\u662f\u5e38\u6570\uff0ca\u5fc5\u4e3a\u6b63\u53f7\u7684\uff0c\u8fd9\u662f\u6570\u5b66\u4e0a\u505a\u65b9\u7a0b\u7684\u5e38\u8bc6\uff0c\u8981\u5c06\u7c7b\u4f3c\u4e8e\u20146x2+8x+2\u7684\u5f0f\u5b50\uff0c\u8f6c\u53d8\u62106x2-8x-2\uff0c\u6240\u4ee5a\u5fc5\u4e3a\u6b63\u53f7\uff0c\u53e6\u5916\uff0c\u8fd9\u91cc\u6ca1\u53d1\u6253\u51fa\u5e73\u65b9\uff0c\u4f46\u662f\u4f60\u5e94\u8be5\u4e0d\u4f1a\u770b\u9519\u628a\u3002\uff09
\u9996\u5148,\u4e00\u822c\u9898\u76ee\u4e0d\u4f1a\u5f88\u53d8\u6001\u7684\u5c06\u4e8c\u6b21\u9879\u7684\u7cfb\u6570\uff08\u5373a\uff09\u641e\u5f97\u5f88\u5927\uff0c
\u6240\u4ee5\uff0c\u8fd9\u6709\u4e00\u5b9a\u7684\u8bc0\u7a8d\uff0c\u9996\u5148\u5217\u51faa\u7684\u6240\u6709\u56e0\u5b50\uff0c\u4f8b\u5982\uff0ca\u662f6\uff0c\u5219\u5217\u51fa\uff082\uff0c3\uff09
(1\uff0c6)\uff0c\u7136\u540e\u5bf9c\u4e5f\u4f5c\u540c\u6837\u5730\u5904\u7406\u3002\u63a5\u7740\uff0c\u770bb\uff0cc\u7684\u7b26\u53f7\u3002\u5982\u679c\uff0cb\u662f\u6b63\u53f7\uff0cc\u4e5f\u662f\u6b63\u53f7\uff0c\u90a3\u4e48\u6bd4\u8f83\u597d\u5904\u7406\uff0c\u628ac\u5206\u6210\u4e24\u4e2a\u6b63\u53f7\u7684\u56e0\u5b50\uff0c\u548ca\u7684\u56e0\u5b50\u51d1\u4e00\u51d1\uff08\u51d1\u5c31\u6ca1\u6709\u8bc0\u7a8d\u4e86\uff0c\u4e00\u822c\u4e0d\u4f1a\u8bd5\u5230\u592a\u591a\u6b21\u3002\u5982\u679c\u4f60\u521a\u5f00\u59cb\u5b66\u4f1a\u8fd9\u4e2a\uff0c\u5f53\u7136\u8fd8\u4e0d\u4f1a\u63a5\u89e6\u5230\u5c06a\uff0cc\u5206\u6210\u5e26\u6709\u5206\u6570\u4e24\u4e2a\u56e0\u6570\uff0c\u90a3\u65f6\u4e00\u5143\u4e8c\u6b21\u65b9\u7a0b\u624d\u5b66\u7684\uff09\u3002\u5982\u679cb\u65f6\u6b63\u53f7\uff0cc\u662f\u8d1f\u53f7\uff0c\u90a3\u4e48\uff0c\u4e00\u822c\u662f\u5c06c\u5206\u6210\u5dee\u8f83\u5927\u7684\u4e24\u4e2a\u56e0\u5b50\uff0c\u7136\u540e\u6b63\u53f7\u7ed9\u5927\u6570\uff0c\u4e0ea\u7684\u56e0\u5b50\u51d1\u3002
\u7136\u540e\uff0c\u5982\u679cb\u7684\u7b26\u53f7\u662f\u8d1f\u53f7\uff0c\u90a3\u4e48\u57fa\u672c\u6b65\u9aa4\u4e00\u6837\uff0c\u8981\u53cd\u4e00\u53cd\u7684\u5730\u65b9\u53cd\u4e00\u53cd\u3002
\u5c31\u50cf\u4f60\u7ed9\u7684\u8fd9\u9898\u3002\u9996\u51482\u53ea\u80fd\u5206\u62101*2\uff0c\u90a3\u4e48\u5148\u653e\u4e00\u8fb9\u3002\u7136\u540eb\u662f\u8d1f\u53f7\u7684\uff0c\u90a3\u4e48\u5c06c\u5206\u6210\u4e24\u4e2a\u5dee\u8f83\u5927\u7684\u56e0\u5b50\uff0c\u8fd9\u91cc\u5f53\u7136\u4e5f\u53ea\u80fd\u662f1\u30012\uff0c\u7531\u4e8eb\u662f\u8d1f\u7684\uff0c\u90a3\u4e48\u628a\u6b63\u53f7\u7ed9\u8f83\u5c0f\u7684\u6570\uff0c\u7136\u540e\u5217\u5f0f\u5b50\u3002
1 -2
*
2 1 2*(-2)+1*1=-3
\u5982\u679c\u4e0d\u5bf9\uff0c\u90a3\u4e48\u5c31\u8c03\u6574\u4e00\u4e0b\u4f4d\u7f6e\u3002\u53e6\u5916\uff0c\u8bb0\u4f4f\uff0c\u5217\u5982\u4e0a\u5f0f\u5b50\u65f6\uff0c\u662f\u4ea4\u53c9\u76f8\u4e58\uff1a1*1\uff0c2*-2\uff0c\u4f46\u662f\u5199\u5f0f\u5b50\u7684\u65f6\u5019\u8981\u6a2a\u7740\u5199\uff0c\uff081x-2\uff09\uff082-1\uff09\u6240\u4ee5\uff0c
2*(-2)+1*1=\uff081x-2\uff09\uff082-1\uff09\u5c31\u662f\u89e3\u3002
\u660e\u767d\u4e86\u5417\uff1f
\u89e3\u8fd9\u7c7b\u9898\uff0c\u6ca1\u6709\u4ec0\u4e48\u5fc5\u4f1a\u7684\u6280\u5de7\uff0c\u4ee5\u4e0a\u7684\u53ea\u662f\u4e00\u4e9b\u76ae\u6bdb\uff0c\u4f46\u53ef\u4ee5\u7ed9\u521d\u5b66\u8005\u8bb2\u89e3\uff0c\u5e76\u63d0\u9ad8\u521d\u5b66\u8005\u4e00\u5b9a\u7684\u89e3\u9898\u901f\u5ea6\uff0c\u6240\u4ee5\u8fd8\u662f\u8bb0\u4f4f\u4e3a\u597d\u3002
\u5728\u53c8\u95ee\u9898\u53bb\u8bf7\u6559\u6570\u5b66\u8001\u5e08\u597d\u4e86\uff0c\u4ed6\u4eec\u624d\u66f4\u6709\u7ecf\u9a8c\u3002
\u795d\u4f60\u597d\u8fd0\u3002
1/3-1/2=1/6 绝对值
3/5-1/2=1/10
a/b = 1/10 / 1/6
图:
1/3 1/10
1/2
3/5 1/6
绛旓細1銆佸崄瀛楃浉涔樻硶鐨勬柟娉曪細鍗佸瓧宸﹁竟鐩镐箻绛変簬浜屾椤圭郴鏁帮紝鍙宠竟鐩镐箻绛変簬甯告暟椤癸紝浜ゅ弶鐩镐箻鍐嶇浉鍔犵瓑浜庝竴娆¢」绯绘暟銆2銆佸崄瀛楃浉涔樻硶鐨勭敤澶勶細锛1锛夌敤鍗佸瓧鐩镐箻娉曟潵鍒嗚В鍥犲紡銆傦紙2锛夌敤鍗佸瓧鐩镐箻娉曟潵瑙d竴鍏冧簩娆℃柟绋嬨3銆佸崄瀛楃浉涔樻硶鐨勪紭鐐癸細鐢ㄥ崄瀛楃浉涔樻硶鏉ヨВ棰樼殑閫熷害姣旇緝蹇紝鑳藉鑺傜害鏃堕棿锛岃屼笖杩愮敤绠楅噺涓嶅ぇ锛屼笉瀹规槗鍑洪敊銆...
绛旓細鍗佸瓧鐩镐箻娉曟槸涓绉嶇敤浜庡垎瑙e洜寮忕殑鏁板鏂规硶锛岄傜敤浜庣郴鏁颁笉涓1鐨勪簩娆′笁椤瑰紡銆傞氳繃杩欑鏂规硶锛屽彲浠ュ皢涓涓簩娆′笁椤瑰紡鎷嗗垎鎴愪袱涓竴娆″洜寮忕殑涔樼Н锛屼粠鑰岀畝鍖栬В棰樿繃绋嬨備竴銆佺郴鏁颁笉涓轰竴鐨勫崄瀛楃浉涔樻硶鐨勪箻绉叿浣撴楠 1銆佸皢浜屾椤圭郴鏁板垎瑙h川鍥犳暟銆傚浜庝簩娆¢」2x^2 + 3x + 5锛屽皢2鍒嗚В涓2脳1銆2銆佸皢甯告暟椤瑰垎瑙h川...
绛旓細褰㈠锛歛x²+bx+c=0鐨勫舰寮忓彲浠ョ敤鍗佸瓧鐩镐箻娉锛屼絾鏈夌壒娈婃儏鍐点傛壘鍒版煇涓暣鏁颁娇寰楋細a=p路q(p銆乹涓烘暣鏁)锛宑=m路n(m銆乶涔熶负鏁存暟)锛屼笖b=pn+mq杩欐牱鍘熷紡灏卞彲浠ュ啓鎴(px+m)(qx+n)=0銆 渚嬶細2x²+6x+4=0锛屽崄瀛楃浉涔樻潵瑙o細2=1脳2锕1銆2閮戒负鏁存暟锕氾紝4=2脳2锛屼笖6=1脳2+2脳...
绛旓細鍗佸瓧鐩镐箻娉曠殑鍏蜂綋鏂规硶锛氬崄瀛楀乏杈圭浉涔樼瓑浜庝簩娆¢」绯绘暟,鍙宠竟鐩镐箻绛変簬甯告暟椤,浜ゅ弶鐩镐箻鍐嶇浉鍔犵瓑浜庝竴娆¢」绯绘暟.搴旂敤鍗佸瓧鐩镐箻娉曡В棰樼殑瀹炰緥锛氫緥1鎶妋²+4m-12鍒嗚В鍥犲紡 鍒嗘瀽锛氭湰棰樹腑甯告暟椤-12鍙互鍒嗕负-1脳12,-2脳6,-3脳4,-4脳3,-6脳2,-12脳1褰-12鍒嗘垚-2脳6鏃,鎵嶇鍚堟湰棰 鍥犱负 1 -2 1 鈺 ...
绛旓細1銆佸崄瀛楃浉涔樻硶鐨勬柟娉曪細鍗佸瓧宸﹁竟鐩镐箻绛変簬浜屾椤圭郴鏁帮紝鍙宠竟鐩镐箻绛変簬甯告暟椤癸紝浜ゅ弶鐩镐箻鍐嶇浉鍔犵瓑浜庝竴娆¢」绯绘暟銆2銆佸崄瀛楃浉涔樻硶鐨勭敤澶勶細锛1锛夌敤鍗佸瓧鐩镐箻娉曟潵鍒嗚В鍥犲紡銆傦紙2锛夌敤鍗佸瓧鐩镐箻娉曟潵瑙d竴鍏冧簩娆℃柟绋嬨3銆佸崄瀛楃浉涔樻硶鐨勪紭鐐癸細鐢ㄥ崄瀛楃浉涔樻硶鏉ヨВ棰樼殑閫熷害姣旇緝蹇紝鑳藉鑺傜害鏃堕棿锛岃屼笖杩愮敤绠楅噺涓嶅ぇ锛屼笉瀹规槗鍑洪敊銆...
绛旓細鍗佸瓧鐩镐箻娉鏄洜寮忓垎瑙d腑鍗佸洓绉嶆柟娉曚箣涓銆傚崄瀛楃浉涔樻硶 鍗佸瓧鐩镐箻娉曠殑鏂规硶绠鍗曟潵璁插氨鏄細鍗佸瓧宸﹁竟鐩镐箻鐨勭Н涓轰簩娆¢」锛屽彸杈圭浉涔樼殑绉负甯告暟椤癸紝浜ゅ弶鐩镐箻鍐嶇浉鍔犵瓑浜庝竴娆¢」銆傚師鐞嗗氨鏄繍鐢ㄤ簩椤瑰紡涔樻硶鐨勯嗚繍绠楁潵杩涜鍥犲紡鍒嗚В銆傚崄瀛楃浉涔樻硶鑳界敤浜庝簩娆′笁椤瑰紡锛堜竴鍏冧簩娆″紡锛夌殑鍒嗚В鍥犲紡銆傚浜庡儚ax²+bx+c=(a...
绛旓細1銆佸崄瀛楃浉涔樻硶鐨勬柟娉曟槸鍗佸瓧宸﹁竟鐩镐箻绛変簬浜屾椤圭郴鏁锛屽彸杈圭浉涔樼瓑浜庡父鏁伴」锛屼氦鍙夌浉涔樺啀鐩稿姞绛変簬涓娆¢」绯绘暟銆2銆佸崄瀛楃浉涔樻硶鐨勭敤澶勬槸鐢ㄥ崄瀛楃浉涔樻硶鏉ュ垎瑙e洜寮鎴栫敤鍗佸瓧鐩镐箻娉曟潵瑙d竴鍏冧簩娆℃柟绋嬨3銆佸崄瀛楃浉涔樻硶鐨勪紭鐐规槸鐢ㄥ崄瀛楃浉涔樻硶鏉ヨВ棰樼殑閫熷害姣旇緝蹇紝鑳藉鑺傜害鏃堕棿锛岃屼笖杩愮敤绠楅噺涓嶅ぇ锛屼笉瀹规槗鍑洪敊銆4銆佸崄瀛楃浉涔...
绛旓細鍗佸瓧鐩镐箻娉曠殑鏂规硶鍙h瘈锛鍗佸瓧宸﹁竟鐩镐箻绛変簬浜屾椤圭郴鏁锛屽彸杈圭浉涔樼瓑浜庡父鏁伴」锛屼氦鍙夌浉涔樺啀鐩稿姞绛変簬涓娆¢」绯绘暟銆傚崄瀛楃浉涔樻硶鐨勭敤澶勶細1銆鐢ㄥ崄瀛楃浉涔樻硶鏉ュ垎瑙e洜寮銆2銆佺敤鍗佸瓧鐩镐箻娉曟潵瑙d竴鍏冧簩娆℃柟绋嬨傚崄瀛楃浉涔樻硶鐨勪紭鐐癸細鐢ㄥ崄瀛楃浉涔樻硶鏉ヨВ棰樼殑閫熷害姣旇緝蹇紝鑳藉鑺傜害鏃堕棿锛岃屼笖杩愮敤绠楅噺灏忥紝涓嶅鏄撳嚭閿欍傚崄瀛楀垎瑙f硶鑳...
绛旓細鍗佸瓧鐩镐箻娉灏辨槸锛氬崄瀛楀乏杈逛袱鏁扮浉涔樼瓑浜庝簩娆¢」鐨勭郴鏁帮紝鍗佸瓧鍙宠竟涓ゆ暟鐩镐箻绛変簬甯告暟椤圭殑鍊硷紝鍗佸瓧浜ゅ弶鐩镐箻锛屽啀鐩稿姞绛変簬涓娆$殑椤圭郴鏁般備緥濡傦細x²-3x+2 = 1 -1 鈺 1 -2 宸﹁竟 1脳1 = 1 (浜屾椤 x² 鐨勭郴鏁)鍙宠竟 -1脳(-2) = 2 (甯告暟椤圭殑鍊)涓棿 1脳(-2) + 1脳(...
绛旓細鈥滃崄瀛楃浉涔樻硶鈥濈敤浜庝竴鍏冧簩娆℃柟绋嬬殑姹傝В锛屾槸鍥犲紡鍒嗚В鐨勬柟娉曚箣涓锛岀啛缁冩帉鎻¤兘鎴愬嶆彁鍗囪绠楅熷害锛佷竴銆佸熀鏈師鐞 浜屻佷娇鐢ㄦ柟娉 杩愮敤涓婅堪绛夊紡鐨勯嗚繍绠楋紝鍦ㄤ粎浠呭凡鐭ョ瓑鍙峰彸杈圭殑鍐呭鎶婂乏杈圭殑寮忓瓙鍑戝嚭鏉ャ傚嵆锛鍗佸瓧宸﹁竟鐩镐箻绛変簬浜屾椤圭郴鏁锛屽彸杈圭浉涔樼瓑浜庡父鏁伴」锛屼氦鍙夌浉涔樺啀鐩稿姞绛変簬涓娆¢」绯绘暟銆傝繖鍙ヨ瘽浠涔堟剰鎬濓紝鐢ㄦ枃瀛...