5个5用数学怎么算到等于20呀？
\u6570\u5b66\uff0c5\u4e58\u4ee58\u5206\u4e4b\u4e00\u7b49\u4e8e\u591a\u5c11\uff0c\u628a\u7b97\u7684\u65b9\u6cd5\u8bf4\u51fa\u6765\uff0c\u8c22\u8c22\uff015*1/8=5/8
5\u4e5f\u5c31\u662f5/1\u518d\u4e58\u4ee51/8\u5206\u5b50\u76f8\u4e58\uff0c\u5206\u6bcd\u76f8\u4e58\u5373\u53ef
1/1*3 +1/2*4 +1/3*5 +1/4*6 +......+1/17*19 +1/18*20
=(1/1*3 +1/3*5+......+1/17*19 )+(1/2*4 +1/4*6 +......+1/18*20 )
=1/2 *[(1 - 1/3)+(1/3 - 1/5)+......+(1/17 - 1/19)] + 1/2 *[(1/2 - 1/4)+(1/4 - 1/6)+......+(1/18 - 1/20)]
=1/2*[(1-1/3+1/3-1/5+......+1/17-1/19)+(1/2-1/4+1/4-1/6+......+1/18-1/20)]
=1/2*[(1-1/19)+(1/2-1/20)]
=1/2*(18/19 +9/20)
=1/2* (521/380)
=521/760
\u8fd9\u9053\u9898\u5229\u7528\u4e86\u4e24\u6b21\u5206\u6570\u62c6\u5206\u7684\u65b9\u6cd5\u3002
\u516c\u5f0f\uff1a1/n(n+d)=1/d *[1/n - 1/n+d]
LS重复了~
(5*5-5)/5*5
5×5×5－5的2次平方－5
绛旓細5+5鍗5+5-5=15,锛5-5+5-5锛*5=0,5+5+5-5-5=5
绛旓細鏂规硶1锛(5x5x5-5)梅5=24 鏂规硶2锛(5-5梅5梅5)x5=24
绛旓細1. 浜斾釜5涓棿鍔犱笂鏁板绗﹀彿锛屼娇寰楃瓑寮忕粨鏋滀负9锛屼竴涓彲鑳界殑瑙ｆ硶鏄細(5x5-5)/5+5=9銆2. 鎴戜滑鍙互鍏璁＄畻鎷彿鍐呯殑涔樻硶鍜屽噺娉曪紝鍗5涔樹互5绛変簬25锛屽啀鍑忓幓5绛変簬20銆3. 鐒跺悗灏20闄や互5锛屽緱鍒4銆4. 鏈鍚庯紝灏4鍔犱笂5锛岀粨鏋滅‘瀹炴槸9銆5. 鍥犳锛(5x5-5)/5+5=9 鏄竴涓弧瓒虫潯浠剁殑绛夊紡銆
绛旓細5*[5-(5/5)/5]=24
绛旓細5脳(5梅5+5梅5)=10 5脳5-5-5-5=10
绛旓細鏄35銆20+5脳3 =20+15 =35 涔樻硶鐨璁＄畻娉曞垯锛氭暟浣嶅榻愶紝浠庡彸杈硅捣锛屼緷娆＄敤绗簩涓洜鏁版瘡浣嶄笂鐨勬暟鍘讳箻绗竴涓洜鏁帮紝涔樺埌鍝竴浣嶏紝寰楁暟鐨勬湯灏惧氨鍜岀浜屼釜鍥犳暟鐨勫摢涓浣嶅榻愩備袱浣嶆暟鐨勫崄浣嶅樊1锛屼釜浣嶇殑涓ゆ暟鍒欐槸鐩歌ˉ鐨勩傚锛48脳52 12脳28 39脳11 48脳32 96脳84 75脳65鍗崇敤杈冨ぇ鐨勫洜鏁扮殑鍗佷綅鏁...
绛旓細5*1+2+3=10; 1+2+3+5=11; 2*3+1+5=12;2*(3+1)+5=13; (5+2)*(3-1)=14; 5*3/(2-1)=15; 5*3+2-1=16; 5*3+2*1=17;5*3+2+1=18; (5-1)*(3+2)=20 19 鍙敤鍥涘垯杩愮畻鍜屾嫭鍙风畻涓嶅嚭鏉ヤ簡銆傚鏋滃彲浠ョ敤骞虫柟鐨勮瘽鍙互 濡傦細5骞虫柟锛25锛-3-2-1=19 ...
绛旓細5*5/5/5=1
绛旓細鍙互鍒楀紡涓猴紙9+9锛壝9+9+9锛20銆傛棰樿繍鐢ㄤ簡鏁板涓姞銆佸噺銆侀櫎銆佹嫭鍙风殑褰㈠紡锛屽皢5涓9閲嶆柊鍒楀紡杩愮畻銆傛寜鐓у洓鍒欒繍绠楀畾寰嬶紝鍏堟嫭鍙枫佸悗涔橀櫎锛屽啀鍔犲噺锛屾嫭鍙蜂腑9+9锛18锛18鍐嶉櫎浠9绛変簬2锛2+9锛11锛11+9锛20锛屾濂芥寜鐓ц姹備娇鐢ㄤ簡5涓9锛屽緱鏁绛変簬20銆
绛旓細銆愶紙9+9锛夐櫎浠9銆+9+9=20
