几道初中的奥数题目1.已知x,y,z都为实数,a>0,且,满足x+y+z=a,x^2+y^2+z^2=1/2a^2,求y
1、因为x、y、z都是未知数,明显y的取值范围是实数集；2、证明：(2b-c-a)^2-4(2a-b-c)(2c-a-b)
=4b^2-4bc-4ba+a^2+c^2+2ac-16ac+8a^2+8ab+8bc-4ab-4b^2+8c^2-4ac-4bc
=9a^2+9c^2-18ac=9(a-c)^2；
3、（bc+c+p）*a小于等于0；
4、由y=2x/(x^2+x-1)得,yx^2+yx-2x-y=0要有意义,
所以（y-2）^2+4y=y^2+4要大于或等于0,所以y属于实数；
5、(m^2-m-1)*m^3+(m^2-m-1)*m^2+(m^2-m-1)*m= 0 =m^5-5m-3
m^5+n^5 = 5(m+n)+6 = 5+6=11 (m+n=1)
6、(st+4s+1)/t = -5
7、a = 0
8、m要大于等于0.75且小于等于7.
绛旓細4銆佺敱y=2x/(x^2+x-1)寰,yx^2+yx-2x-y=0瑕佹湁鎰忎箟,鎵浠ワ紙y-2锛塣2+4y=y^2+4瑕佸ぇ浜庢垨绛変簬0,鎵浠灞炰簬瀹炴暟锛5銆(m^2-m-1)*m^3+(m^2-m-1)*m^2+(m^2-m-1)*m= 0 =m^5-5m-3 m^5+n^5 = 5(m+n)+6 = 5+6=11 (m+n=1)6銆(st+4s+1)/t = -5 7銆乤 ...
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