-x1的三次方4次方-[1-1-(0.5x1/2)]x6

比较大小:1的2次方&2的1次方 2的3次方&3的2次方 3的4次方&4的3次方 次方&次方整个题目是:比较下列数的大小:1的2次方&2的1次方 2的3次方&3的2次方 3的4次方&4的3次方 4的5次方&5的4次方 5的6次方&6的5次方 次方&次方 还有n的(n+1)次方&(n+1)的n次方
分类:数学
1^25^4;5^6>6^5;这些可以自己算啦.于是得规律:①当n.
0所以 x=1当x>1,f'(x)>0,f(x) 单调递增 [1,+∞)当 0">f'(x)=x-1/x=0,x=1 或 x=-1又 x>0所以 x=1当x>1,f'(x)>0,f(x) 单调递增 [1,+∞)当 0
已知函数f(x)=loga(x2+1+x)根号+1,开根号的是(x2+1+x),若f(log3b)=5,那么f(log1/3b)是多少rt
如果log3b=k,那么b=3的k方;则log1/3b=k*log(1/3)3=-k;所以解出log3b为根号(a的8方-3/4)-1/2;log(1/3)b=-根号(a的8方-3/4)+1/2.
103.1第二年:W2=25*X12+36*X22+32*X32+15*X42+31*X52+28*X62+22*X72+12*X82+25*X11*0.9+36*X21*0.9+32*X31*0.9+15*X41*0.9+31*X51*0.9+28*X61*0.9+22*X71*0.9+12*X81*0.9W2>117.7第三年:W3=25*X13+36*X23+32*X33+15*X43+31*X53+28*X63+22*X73+12*X83+25*X12*0.9+36*X22*0.9+32*X32*0.9+15*X42*0.9+31*X52*0.9+28*X62*0.9+22*X72*0.9+12*X82*0.9+25*X11*0.81+
36*X21*0.81+32*X31*0.81+15*X41*0.81+31*X51*0.81+28*X61*0.81+22*X71*0.81+12*X81*0.81W3>132minf=F1+F2+F3=5*X11+7*X21+5*X31+4*X41+6*X51+5*X61+5*X71+3*X81+5*X12+7*X22+5*X32+4*X42+6*X52+5*X62+5*X72+3*X82+5*X13+7*X23+5*X33+4*X43+6*X53+5*X63+5*X73+3*X83">用lingo求解:编号 1 2 3 4 5 6 7 8打井费用 5 7 5 4 6 5 5 3当年产水 25 36 32 15 31 28 22 124 符号说明Xij
0—1变量,表示第i号井在第j年的施工情况,Xij=1第i号井在第j年施工,Xij=0表示不施工Fj j年打井总费用第一年:W1=25*X11+36*X21+32*X31+15*X41+31*X51+28*X61+22*X71+12*X81;W1>103.1第二年:W2=25*X12+36*X22+32*X32+15*X42+31*X52+28*X62+22*X72+12*X82+25*X11*0.9+36*X21*0.9+32*X31*0.9+15*X41*0.9+31*X51*0.9+28*X61*0.9+22*X71*0.9+12*X81*0.9W2>117.7第三年:W3=25*X13+36*X23+32*X33+15*X43+31*X53+28*X63+22*X73+12*X83+25*X12*0.9+36*X22*0.9+32*X32*0.9+15*X42*0.9+31*X52*0.9+28*X62*0.9+22*X72*0.9+12*X82*0.9+25*X11*0.81+
36*X21*0.81+32*X31*0.81+15*X41*0.81+31*X51*0.81+28*X61*0.81+22*X71*0.81+12*X81*0.81W3>132minf=F1+F2+F3=5*X11+7*X21+5*X31+4*X41+6*X51+5*X61+5*X71+3*X81+5*X12+7*X22+5*X32+4*X42+6*X52+5*X62+5*X72+3*X82+5*X13+7*X23+5*X33+4*X43+6*X53+5*X63+5*X73+3*X83
103.1;!第二年:;W2=25*X12+36*X22+32*X32+15*X42+31*X52+28*X62+22*X72+12*X82+25*X11*0.9+36*X21*0.9+32*X31*0.9+15*X41*0.9+31*X51*0.9+28*X61*0.9+22*X71*0.9+12*X81*0.9;W2>117.7;!第三年:;W3=25*X13+36*X23+32*X33+15*X43+31*X53+28*X63+22*X73+12*X83+25*X12*0.9+36*X22*0.9+32*X32*0.9+15*X42*0.9+31*X52*0.9+28*X62*0.9+22*X72*0.9+12*X82*0.9+25*X11*0.81+36*X21*0.81+32*X31*0.81+15*X41*0.81+31*X51*0.81+28*X61*0.81+22*X71*0.81+12*X81*0.81;W3>132;min=5*X11+7*X21+5*X31+4*X41+6*X51+5*X61+5*X71+3*X81+5*X12+7*X22+5*X32+4*X42+6*X52+5*X62+5*X72+3*X82+5*X13+7*X23+5*X33+4*X43+6*X53+5*X63+5*X73+3*X83;@bin(x11);@bin(x21);@bin(x31);@bin(x41);@bin(x51);@bin(x61);@bin(x71);@bin(x81);@bin(x12);@bin(x22);@bin(x32);@bin(x42);@bin(x52);@bin(x62);@bin(x72);@bin(x82);@bin(x13);@bin(x23);@bin(x33);@bin(x43);@bin(x53);@bin(x63);@bin(x73);@bin(x83); x11+x12+x13x21+x22+x23x31+x32+x33x41+x42+x43x51+x52+x53x61+x62+x63x71+x72+x73x81+x82+x83
">!第一年:;W1=25*X11+36*X21+32*X31+15*X41+31*X51+28*X61+22*X71+12*X81;W1>103.1;!第二年:;W2=25*X12+36*X22+32*X32+15*X42+31*X52+28*X62+22*X72+12*X82+25*X11*0.9+36*X21*0.9+32*X31*0.9+15*X41*0.9+31*X51*0.9+28*X61*0.9+22*X71*0.9+12*X81*0.9;W2>117.7;!第三年:;W3=25*X13+36*X23+32*X33+15*X43+31*X53+28*X63+22*X73+12*X83+25*X12*0.9+36*X22*0.9+32*X32*0.9+15*X42*0.9+31*X52*0.9+28*X62*0.9+22*X72*0.9+12*X82*0.9+25*X11*0.81+36*X21*0.81+32*X31*0.81+15*X41*0.81+31*X51*0.81+28*X61*0.81+22*X71*0.81+12*X81*0.81;W3>132;min=5*X11+7*X21+5*X31+4*X41+6*X51+5*X61+5*X71+3*X81+5*X12+7*X22+5*X32+4*X42+6*X52+5*X62+5*X72+3*X82+5*X13+7*X23+5*X33+4*X43+6*X53+5*X63+5*X73+3*X83;@bin(x11);@bin(x21);@bin(x31);@bin(x41);@bin(x51);@bin(x61);@bin(x71);@bin(x81);@bin(x12);@bin(x22);@bin(x32);@bin(x42);@bin(x52);@bin(x62);@bin(x72);@bin(x82);@bin(x13);@bin(x23);@bin(x33);@bin(x43);@bin(x53);@bin(x63);@bin(x73);@bin(x83); x11+x12+x13x21+x22+x23x31+x32+x33x41+x42+x43x51+x52+x53x61+x62+x63x71+x72+x73x81+x82+x83
0,cosa>0所以只有2sina-3cosa=0sina=3cosa/2sin?a+cos?a=1所以cos?a=4/13sin(a+π/4)=(√2/2)(sina+cosa)sin2a+cos2a+1=2sinacosa+2cos?a-1+1=2cosa(sina+cosa)原式=(√2/2)/2cosa=(√2/2)/(4/√13)=√26/8">2(sina)^2-sinacosa-3(cosa)^2=0(2sina-3cosa)(sina+cosa)=0a属于(0,π/2)所以 sina>0,cosa>0所以只有2sina-3cosa=0sina=3cosa/2sin?a+cos?a=1所以cos?a=4/13sin(a+π/4)=(√2/2)(sina+cosa)sin2a+cos2a+1=2sinacosa+2cos?a-1+1=2cosa(sina+cosa)原式=(√2/2)/2cosa=(√2/2)/(4/√13)=√26/8
函数f(x)=ax2+2x+1在区间(-∞,0)上至少有一个零点,则实数a的取值范围是______.
a=0时,f(x)=2x+1零点为x=-,在原点左侧,符合题意a<0时,△=4-4a>0恒成立,故f(x)有零点,且x1ox2<0,至少有一个零点为负,符合题意a>0时,△=4-4a≥0,则a≤1,两个零点满足x1+x2=-<0,x1ox2=>0,x1,x2均为负值,符合题意;综上,a≤1,故答案为:(-∞,1].
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