如图1.两车同时出发相向而行,两车之间的距离y和行驶时间x的关系如图所示,两车出发后()相遇。 (2分)两辆汽车在同一平直公路上同时出发,其位置x与时间t的...
\u7532\u8f66\u4eceA \u5730\u9a76\u5f80 C\u5730\uff0c\u5728C \u505c\u7559\u4e00\u6bb5\u65f6\u95f4\u540e\uff0c\u8fd4\u56deA\u5730\uff0c\u4e59\u8f66\u4eceB\u5730\u7ecfC\u5730A\u9a76\u5f80\uff0c\u4e24\u8f66\u540c\u65f6\u51fa\u53d1\uff0c\u76f8\u5411\u800c\u884c\uff0c\u540c\u65f6\uff081\uff09\u7531\u9898\u610f\u53ef\u5f97\uff1aA\u3001B\u4e24\u5730\u4e4b\u95f4\u7684\u8ddd\u79bb\u4e3a960km\uff1b\u7532\u3001\u4e59\u4e24\u8f66\u7684\u901f\u5ea6\u548c\uff1a960\u00f76=160\uff08km/h\uff09\uff0c\u6240\u4ee5\u4e59\u8f66\u7684\u901f\u5ea6\uff1a120\u00f7\uff088-6\uff09=60\uff08km/h\uff09\uff0c\u7532\u8f66\u7684\u901f\u5ea6\uff1a160-60=100\uff08km/h\uff09\uff0e\uff082\uff09\u7532\u8f66\u8ffd\u4e59\u8f66120km\uff0c\u65f6\u95f4\u4e3a120\u00f7\uff08100-60\uff09=3\uff08h\uff09\uff0c\u5219D\u70b9\u6a2a\u5750\u6807\u4e3a8+3=11\uff08h\uff09\uff0e\u6240\u4ee5D\u7684\u5750\u6807\u4e3a\uff0811\uff0c0\uff09\uff0c\u56fe\u4e2d\u70b9D\u7684\u5b9e\u9645\u610f\u4e49\u662f\u4e59\u884c\u9a7611\u5c0f\u65f6\u540e\u88ab\u7532\u8ffd\u4e0a\uff1b\uff083\uff09\u7532\u8f66\u5728\u4e59\u8f66\u884c\u9a7614\u5c0f\u65f6\u65f6\u5373\u56de\u5230A\u5730\uff0c\u6b64\u65f6\u4e24\u8f66\u4e4b\u95f4\u76f8\u8ddd120\u5343\u7c73\uff0c\u518d\u7ecf\u8fc72\u5c0f\u65f6\uff0c\u4e24\u8f66\u4e4b\u95f4\u8ddd\u79bb\u7f29\u5c0f\u81f3\u96f6\uff0c\u5982\u56fe\u6240\u793a\uff1b\uff084\uff09\u5f5311\u2264x\u226416\u65f6\uff0c\u4e24\u8f66\u4e4b\u95f4\u6700\u8fdc\u76f8\u8ddd120\u5343\u7c73\uff0e\u6240\u4ee5\uff0c\u5f5311\u2264x\u226414\u65f6\uff0cy=40x-440 \uff08\u8fc7\uff0811\uff0c0\uff09\u548c\uff0814\uff0c120\uff09\u7684\u7ebf\u6bb5\uff09\uff0e\u5f5314\u2264x\u226416\u65f6\uff0cy=-60x+960 \uff08\u8fc7\uff0814\uff0c120\uff09\u548c\uff0816\uff0c0\uff09\u7684\u7ebf\u6bb5\uff09\uff0e\u6545\u7b54\u6848\u4e3a\uff081\uff09960km\uff1b100\uff0c60\uff1b\uff082\uff09\uff0811\uff0c0\uff09\uff0c\u4e59\u884c\u9a7611\u5c0f\u65f6\u540e\u88ab\u7532\u8ffd\u4e0a\uff0e
30\uff1b450\uff0e \u8bd5\u9898\u5206\u6790\uff1a\u7531\u56fe\u5f97\u51fa\u7532\u4e59\u4e24\u8f66\u90fd\u505a\u5300\u901f\u76f4\u7ebf\u8fd0\u52a8\uff0c\u5728t=50s\u65f6\uff0c\u7532\u8f66\u884c\u9a76\u7684\u8def\u7a0bs \u7532 =1500m\uff0c\u7532\u7684\u901f\u5ea6 \uff1b\u5728t=50s\u65f6\uff0c\u7532\u5904\u57281500m\u7684\u4f4d\u7f6e\uff0c\u4e59\u5904\u57281050m\u7684\u4f4d\u7f6e\uff0c\u4e24\u8f66\u76f8\u8ddd450m\u7684\u8ddd\u79bb\u3002
j解:(1)由图2可知:骑车人从9时出发离开A地,12时到达B地。(由9时时,y=0,12时,y=45千米可得)。(2)由图可知,13时从B地出发,15时到A地,用了2小时。
(3)V=45/(12-9)=15千米/小时。
先求A,B 坐标,再求AB之间的距离。套公式。就可得。
绛旓細j瑙o細锛1锛夌敱鍥2鍙煡锛氶獞杞︿汉浠9鏃鍑哄彂绂诲紑A鍦帮紝12鏃跺埌杈綛鍦般傦紙鐢9鏃舵椂锛寉=0锛12鏃讹紝y=45鍗冪背鍙緱锛夈(2)鐢卞浘鍙煡锛13鏃朵粠B鍦板嚭鍙戯紝15鏃跺埌A鍦帮紝鐢ㄤ簡2灏忔椂銆傦紙3锛塚=45/锛12-9锛=15鍗冪背/灏忔椂銆
绛旓細锛1锛堿銆丅涓ゅ湴鐩歌窛900鍗冪背锛涙晠绛旀涓猴細900锛庯紙2锛夌偣D鐨勫疄闄呮剰涔夛細涓よ溅4灏忔椂鍚庣浉閬囷紱锛3锛塿鎱=900梅12=75km/h锛寁蹇=900梅4-75=150km/h锛宼蹇=900梅150=6h锛孲鎱=75脳6=450km锛屾墍浠ワ紝鐐笶鐨勫潗鏍囦负锛6锛450锛夛紟
绛旓細瑙o細濡傚浘锛绗涓娆$浉閬囧悗锛屽埌绗簩娆$浉閬囷紝鐢蹭箼涓よ溅鍏琛2涓崟绋嬶紝鐢茶溅琛岀殑璺▼鏄箼杞︾涓娆$浉閬囨椂琛岀殑璺▼鐨2鍊嶅80鍗冪背锛岄偅涔堢涓娆$浉閬囨椂锛岀敳杞︽瘮涔欒溅澶氳80梅2锛40(鍗冪背)鍥犳鍚堣涓涓崟绋嬮渶瑕40梅8锛5灏忔椂锛屽垯鍙畻鍑轰笢瑗夸袱绔欑殑璺濈鏄細40脳5脳2锛40锛360(鍗冪背)绛旓細涓滆タ涓ょ珯鐨勮窛绂绘槸360...
绛旓細AB涓ゅ湴鐩歌窛200鍗冪背銆傜1娆$浉閬囨椂锛屼袱杞鍏辫鍏ㄧ▼1閬嶏紝杩欐椂鐢杞﹁浜85km銆傚埌绗2娆$浉閬囨椂锛屼袱杞﹀叡琛屽叏绋3閬嶏紝杩欐椂鐢茶溅鍏辫浜85脳3=255km锛涚浉閬囩偣绂籅55km銆傛墍浠ワ紝AB鍏ㄧ▼=255-55=200km銆傝В绛旂浉閬囬棶棰樼殑娉ㄦ剰浜嬮」锛1銆佽В绛旇繖绫婚棶棰橈紝瑕佸紕娓呴鎰忥紝鎸夌収棰樻剰鐢诲嚭绾挎鍥撅紝鍒嗘瀽鍚勬暟閲忎箣闂寸殑鍏崇郴锛岄夋嫨瑙...
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绛旓細鍑哄彂鏃,瀹㈣溅銆佽揣杞︾殑閫熷害姣旀槸 6鈭5 ,鍒欑浉閬囨椂瀹㈣溅琛屼簡鍏ㄧ▼鐨 6/(6+5) = 6/11 锛涚浉閬囧悗,瀹㈣溅銆佽揣杞︾殑閫熷害姣斿彉涓 [6脳(1-20%)]鈭禰5脳(1+20%)] = 4鈭5 ,鐩搁亣鍚庤揣杞﹁繕闇瑕佽鍏ㄧ▼鐨 6/11 鍒拌揪鐢插湴,鍚屾牱鏃堕棿鍐呭杞﹁浜嗗叏绋嬬殑 (6/11)脳(4/5) = 24/55 锛涘凡鐭,褰撹揣杞﹀埌杈剧敳鍦...