x 2y 3z=14 3x y 2z=11 2x 3y z=11
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1/15=1/3-1/5;1/35=1/5-1/7;同理可得~最后一项是1/13-1/15~30*(1/3.........-1/15)=8/15
(n+1)(n-1)=n^2-1
i一个字母love四个字母you三个字母此所谓143开个小玩笑啊
1/15=(1/3-1/5)/21/35=(1/5-1/7)/21/63=(1/7-1/9)/2.1/195==(1/13-1/15)/2原题=1+3+5+...+11+(1/3-1/5+1/5-1/
3×5=4²-1则是n(n+2)=(n+1)²-1选D千万别追问
1/15+1/35+1/63+1/99+1/143={[(1/3)-(1/5)]/2}+{[(1/5)-(1/7)]/2}+{[(1/7)-(1/9)]/2}+{[(1/9)-(1/11)]/2}+{
1/3-2/15+3/35-4/63+5/99-6/143=1/3-2(1/3-1/5)+3(1/5-1/7)-4(1/7-1/9)+5(1/9-1/11)-6(1/11-1/13)=1/3-2/3+
1/3+1/15+1/35+1/63+1/99+1/143+1/195+1/255+1/323=1/2(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13
1.d=(a42-a12)/(42-12)=(143-23)/30=4n=12+(an-a12)/d=12+(239-23)/4=662.a1=2.3,d=4.6,an=66.7即求nn=1+(an-
(∏-1)x2y3z是单项式,系数∏-1,次数6
1/3-2/15+3/35-4/63+5/99-6/143=[1/3-2/(3×5)]+[3/(5×7)-4/(7×9)]+[5/(9×11)-6/(11×13)]=1/3×(1-2/5)+1/7×(
(1又7分之4-3分之22+21分之143)*42=11/7×42-22/3×42+143/21×42=66-308+286=44
N*(N+2)=(N+1)2-1
=1+150/(3*5)+150/(5*7)+150/(7*9)+150/(9*11)+150/(11*13)=1+75*(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-
1/3+1/15+1/35+1/63+1/99+1/143=1/2x(1-1/3)+1/2x(1/3-1/5)+.1/2x(1/9-1/11)+1/2(1/11-1/13)=1/2x(1-1/3+1/
∵多项式-3x2y3z+9x3y3z-6x4yz2有三项,∴-3x2y3z,9x3y3z,-6x4yz2中系数的公因数是-3,字母部分公因式为x2yz,故答案为-3x2yz.
(1)180度(2)32度38'15"(3)46度22'42"
(1)原式=-6x3y3z+4x2y3z;(2)原式=4a4b2-4a2b4-4a4b4÷4b2+4a2b4=3a4b2;(3)原式=1232-(123+1)×(123-1)=1232-(1232-1
35分之3+63分之3+99分之1+143分之1=(1/5-1/7+1/7-1/9)x3/2+(1/9-1/11+1/11-1/13)x1/2=(1/5-1/9)x3/2+(1/9-1/13)x1/2