1十3十5十7十...37十39用简便方法计算 1十3十5十7十…十199用简便方法计算
1\u53413\u53415\u53417\u53419\u7b49\u52a0\u523099\u7b80\u4fbf\u65b9\u6cd5\u7b80\u4fbf\u8ba1\u7b97\uff1a1+3+5+7+9+\u2026\u2026+99\u7684\u4e24\u79cd\u89e3\u6cd5\u3002
1\u53413\u53415\u53417\u5341\u2026\u5341199
=\uff081+199\uff09x100\u00f72
=200x100\u00f72
=10000
-----------------------------------------------------------------------------------------
用简便方法计算
1+39=40,3+37=40,5+35=40,7+33=40,9+31=40,11+29=40,13+27=40,15+25=40,17+23=40,19+21=40,40*10=400.
1+3+..+39
=(39+1)x10
=400
如有帮助请采纳,
如对本题有疑问可追问,Good luck!
绛旓細鐢ㄧ畝渚挎柟娉曡绠 1+39=40,3+37=40,5+35=40,7+33=40,9+31=40,11+29=40,13+27=40,15+25=40,17+23=40,19+21=40,40*10=400.
绛旓細涓鍏辨槸50涓暟锛屾妸瀹冨掕繃鏉ワ紝鍐嶄竴瀵逛竴鐩稿姞锛1鍗3鍗5鍗7鈥︹﹀崄95鍗97鍗99 +99+97+95+鈥︹+5+3+1 =100+100+100+鈥︹+100+100+100锛50涓100锛=100x50=5000 閭d箞鍘熸潵鐨1鍗3鍗5鍗7鈥︹﹀崄95鍗97鍗99=5000梅2=2500
绛旓細1鍗3鍗5鍗7...鍗29鍜屾槸濂囨暟锛屼竴鍏辨槸15涓鏁扮殑鍜岋紝鏄鏁般
绛旓細1+3+5+7+鈥︹+85+87+89 =锛1+89锛*45/2=45^2=2025 2025-25=2000锛1+3+5+7+...杩欎釜绠楁槸涓鐩村姞鍒89锛屽啀鍑忓幓25寰楀埌鐨勫拰鏄2000銆
绛旓細1鍗3鍗5鍗7鍗,,,鍗23鍗25鐢ㄧ畝渚挎柟娉曠敤璁$畻 1鍗3鍗5鍗7鍗,,,鍗23鍗25 =锛1+25)x13梅2 锛26x13梅2 锛169
绛旓細1鍗3鍗5鍗7鍗鈥︹﹀崄2019 =(1+2019銆+(3+2017)+(5+2015)+ (7+2013)+鈥︹+(1009+1011)=2020+2020+鈥︹2020 =2020脳505 =1020100
绛旓細1+3+5+鈥︹+39 =锛1+39锛壝20梅2 =40脳20梅2 =800梅2 =400
绛旓細鍙傝
绛旓細1/4(n+1)^2 渚嬪1+3=1/4(3+1)^2=4 1+3+5=1/4(5+1)^2=9 1+3+5+7+...+39=1/4(39+1)^2=400
绛旓細1鍗3鍗5鍗7鍗9绛夊姞鍒99绛変簬2500銆傝В绛旇繃绋嬪涓嬶細1鍗3鍗5鍗7鍗9绛夊姞鍒99 =1+99锛+锛3+97锛+鈥︹+锛47+53锛+锛49+51锛=25*100 =2500