Question

11£®¼ÆËãÌ⣮
£¨1£©1¡Â£¨0.75¡Â$\frac{1}{4}$£©-$\frac{1}{7}$+6¡Â2¡Á3
£¨2£©8$\frac{3}{5}$¡Á2.7+6.2¡Á1.4+3.5¡Á8.6
£¨3£©1$\frac{4}{17}$¡Á£¨2$\frac{2}{3}$-0.75£©+15$\frac{1}{2}$+$\frac{17}{24}$
£¨4£©2+$\frac{2}{3¡Á5}$+$\frac{2}{5¡Á7}$+$\frac{2}{7¡Á9}$+¡­+$\frac{2}{19¡Á21}$£®

Answer 1

·ÖÎö £¨1£©ÏÈËãÀ¨ºÅÄڵģ¬È»ºóÔÙËã³ý·¨ºÍ³Ë·¨£¬×îºóËã¼Ó¼õ·¨£»
£¨2£©ÔËÓó˷¨·ÖÅäÂɼòË㣻
£¨3£©ÏÈËãÀ¨ºÅÄڵģ¬È»ºóÔÙËã³Ë·¨£¬×îºóËã¼Ó·¨£»
£¨4£©ÒòΪÿһÏº¬ÓÐÊý×Ö2£¬ÓÚÊÇÏÈ°Ñ2Ìá³öÀ´£¬ÔÙ°Ñÿ¸ö·ÖÊý²ð³ÉÁ½¸ö·ÖÊýÏà¼õµÄÐÎʽ£¬Í¬¹ú¼Ò¼äÏ໥µÖÏû£¬Çó³ö½á¹û£®

½â´ð ½â£º£¨1£©1¡Â£¨0.75¡Â$\frac{1}{4}$£©-$\frac{1}{7}$+6¡Â2¡Á3
=1¡Â£¨$\frac{3}{4}$¡Â$\frac{1}{4}$£©-$\frac{1}{7}$+3¡Á3
=1¡Â3-$\frac{1}{7}$+9
=$\frac{1}{3}$-$\frac{1}{7}$+9
=$\frac{4}{21}$+9
=9$\frac{4}{21}$

£¨2£©8$\frac{3}{5}$¡Á2.7+6.2¡Á1.4+3.5¡Á8.6
=8.6¡Á2.7+6.2¡Á1.4+3.5¡Á8.6
=8.6¡Á£¨2.7+3.5£©+6.2¡Á1.4
=8.6¡Á6.2+6.2¡Á1.4
=£¨8.6+1.4£©¡Á6.2
=10¡Á6.2
=62

£¨3£©1$\frac{4}{17}$¡Á£¨2$\frac{2}{3}$-0.75£©+15$\frac{1}{2}$+$\frac{17}{24}$
=$\frac{21}{17}$¡Á£¨2$\frac{2}{3}$-$\frac{3}{4}$£©+£¨15$\frac{1}{2}$+$\frac{17}{24}$£©
=$\frac{21}{17}$¡Á$\frac{23}{12}$+$\frac{389}{24}$
=$\frac{161}{68}$+$\frac{389}{24}$
=$\frac{2479}{408}$

£¨4£©2+$\frac{2}{3¡Á5}$+$\frac{2}{5¡Á7}$+$\frac{2}{7¡Á9}$+¡­+$\frac{2}{19¡Á21}$
=2¡Á£¨1+$\frac{1}{3}$-$\frac{1}{5}$+$\frac{1}{5}$-$\frac{1}{7}$+¡­$\frac{1}{19}$-$\frac{1}{21}$£©
=2¡Á£¨1+$\frac{1}{3}$-$\frac{1}{21}$£©
=2¡Á$\frac{9}{7}$
=$\frac{18}{7}$

µãÆÀ ×¢ÒâÔËÓÃÔËËã¼¼ÇÉÁé»î¼òË㣬ͬʱעÒâÔËËã˳Ðò£®