ÌâÄ¿ÄÚÈÝ

17£®ÒÑÖªb£¾a£¾0£¬ÇÒa+b=1£¬ÄÇô£¨¡¡¡¡£©
A£®2ab£¼$\frac{{a}^{4}-{b}^{4}}{a-b}$£¼$\frac{a+b}{2}$£¼bB£®2ab£¼$\frac{a+b}{2}$£¼$\frac{{a}^{4}-{b}^{4}}{a-b}$£¼b
C£®$\frac{{a}^{4}-{b}^{4}}{a-b}$£¼2ab£¼$\frac{a+b}{2}$£¼bD£®2ab£¼$\frac{a+b}{2}$£¼b£¼$\frac{{a}^{4}-{b}^{4}}{a-b}$

·ÖÎö b£¾a£¾0£¬ÇÒa+b=1£¬¿ÉµÃ£º1£¾$b£¾\frac{1}{2}$£¾a£¬ÀûÓÃa2+b2$£¾\frac{£¨a+b£©^{2}}{2}$£¬¿ÉµÃ$\frac{{a}^{4}-{b}^{4}}{a-b}$$£¾\frac{a+b}{2}$£®ÓÉ$\frac{a+b}{2}$£¾$\sqrt{ab}$£¬¿ÉµÃ$2ab£¼\frac{1}{2}$=$\frac{a+b}{2}$£®ÓÉÓÚ$\frac{{a}^{4}-{b}^{4}}{a-b}$-b=£¨a+b£©£¨a2+b2£©-b=a2+b2-b=£¨1-b£©2+b2-b=2b2-3b+1£¬ÔÙÀûÓöþ´Îº¯ÊýµÄÐÔÖʼ´¿ÉµÃ³ö£®

½â´ð ½â£º¡ßb£¾a£¾0£¬ÇÒa+b=1£¬
¡à2a£¼1=a+b£¼2b£¬¡à1£¾$b£¾\frac{1}{2}$£¾a£¬
$\frac{{a}^{4}-{b}^{4}}{a-b}$=£¨a+b£©£¨a2+b2£©=a2+b2$£¾\frac{£¨a+b£©^{2}}{2}$=$\frac{1}{2}$$£¾\frac{a+b}{2}$£¬
ÓÖ$\frac{a+b}{2}$£¾$\sqrt{ab}$£¬¡à$ab£¼\frac{1}{4}$£¬¼´$2ab£¼\frac{1}{2}$=$\frac{a+b}{2}$£®
$\frac{{a}^{4}-{b}^{4}}{a-b}$-b=£¨a+b£©£¨a2+b2£©-b=a2+b2-b=£¨1-b£©2+b2-b=2b2-3b+1=2$£¨b-\frac{3}{4}£©^{2}$-$\frac{1}{8}$$£¼2¡Á£¨\frac{1}{4}£©^{2}$-$\frac{1}{8}$=0£¬
¡à$\frac{{a}^{4}-{b}^{4}}{a-b}$£¼b£®
×ÛÉϿɵãº2ab£¼$\frac{a+b}{2}$$£¼\frac{{a}^{4}-{b}^{4}}{a-b}$£¼b£®
¹ÊÑ¡£ºB£®

µãÆÀ ±¾Ì⿼²éÁ˲»µÈʽµÄ»ù±¾ÐÔÖÊ¡¢º¯ÊýµÄÐÔÖÊ¡¢¡°×÷²î·¨¡±£¬¿¼²éÁËÍÆÀíÄÜÁ¦Óë¼ÆËãÄÜÁ¦£¬ÊôÓÚÖеµÌ⣮

Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿

Î¥·¨ºÍ²»Á¼ÐÅÏ¢¾Ù±¨µç»°£º027-86699610 ¾Ù±¨ÓÊÏ䣺58377363@163.com

¾«Ó¢¼Ò½ÌÍø