求助几个高一对数的数学题``
\u4e00\u4e9b\u9ad8\u4e00\u7684\u5bf9\u6570\u8fd0\u7b97\u6570\u5b66\u98981. a^m\u4e58\u4e0aa^n=______a^(m+n)_________,\u8bbeM=a^m,N=a^n,\u6240\u4ee5MN=a^m\u4e58\u4e0aa^n=a^m+n.\u6240\u4ee5m+n=__loga(MN)______,\u53c8m=log a M,n=log a N,m+n=___log2(MN)______
\u6240\u4ee5log a (M\u4e58\u4e0aN\uff09=_____m+n__________
\u6ce8:\u6211\u5728a\u524d\u9762\u7a7a\u4e86\u683c,\u4ee3\u8868a\u662flog\u7684\u53f3\u4e0b\u89d2\u7684\u4e00\u4e2a\u4ee3\u6570\uff0c\u806a\u660e\u7684\u90fd\u77e5\u9053\uff01
2.\u5982\u679ca>0,\u4e14a\u22601\uff0cM>0,N>0,\u90a3\u4e48\uff0c
\u2460log a(m\u4e58\u4e0aN)=___loga(m)+loga(n)____
\u2461log a (M/N)=___loga(m)-log2(n)______
\u2462log a M^n=___nloga(m)______(n\u2208R)
\u2463log c a/log c b=_______loga(b)________
(a>0,\u4e14a\u22601\uff1bc>0,\u4e14c\u22601\uff1bb>0)
3.\u7528log a x,log a y,log a z\u8868\u793a\u4e0b\u5217\u5404\u5f0f:
\u2460 log a xy/z=loga(x)+loga(y)-loga(z)
\u2461log a \uff08x^2\u4e58\u4e0ay\u7684\u5e73\u65b9\u6839/z\u7684\u7acb\u65b9\u6839)=2loga(x)+[loga(y)]/2-[loga(z)]/3
4.\u6c42\u4e0b\u5217\u5404\u5f0f\u7684\u503c:
\u2460log 2 (4^7\u4e58\u4e0a2^5)=19
\u2461lg0.00001 =-5
5.\u5229\u7528\u5bf9\u6570\u7684\u6362\u5e95\u516c\u5f0f\u5316\u7b80\u4e0b\u5217\u5404\u5f0f:
\u2460log 2 3\u4e58\u4e0alog 3 4\u4e58\u4e0a 4 5\u4e58\u4e0alog 3 2
=(lg3/lg2)*(lg4/lg3)*lg5/lg4)*(lg3/lg2)=lg3lg5/(lg2)^2
\u2461(log 4 3+log 8 3)(log 3 2+log 9 2)
=(lg3/2lg2+lg3/3lg2)(lg2/lg3+lg2/2lg3)
=(4/3)*(3/2)=2
6.
\u2460\u82e5lg(x-y)+1g(x+2y)=1g2+1gx+1gy,\u6c42x/y\u7684\u503c
(x-y)(x+2y)=2xy
x^2-xy-2y^2=0
(x-2y)(x+y)=0
x/y=2,\u6216x/y=-1
\u2461\u5df2\u77e5log 18 9=a,18^b=5,\u7528a,b\u8868\u793alog 36 45
f(x)=lga(x^2-1/lga)^2+4lga-1/lga
\u5f53lga<0\u65f6\uff0c\u6700\u5927\u503c\u4e3a
4lga-1/lga=3
\u89e3\u5f97lga=-1/4
a=10^(-1/4)
0.2^(x+1)=5^(-x-1)<5
\u5373-x-1<1
x>-2
=lg(25/9)+lg9-(lg(7/4)-lg7)
=lg25-lg(1/4)
=lg(25*4)
=lg100
=2.
(lg2)^2+lg2lg5+lg50
=(lg2)^2+lg2lg5+lg5+lg10
=(lg2)^2+lg2lg5+lg5+1.
=lg2*(lg2+lg5)+lg5+1
=lg2+lg5+1
=lg(2*5)+1
=2.
lg(5^2)+2/3lg8+lg5lg20+(lg2)^2
=2lg5+2lg2+lg5lg20+(lg2)^2
=2(lg5+lg2)+lg5*(lg5+lg4)+(lg2)^2
=2+(lg5)^2+2lg2lg5+(lg2)^2
=2+(lg5)^2+lg2*(lg25+lg2)
=2+(lg5)^2+lg2*lg5+lg2
=2+lg5*(lg2+lg5)+lg2
=2+lg5+lg2
=2+lg(5*2)
=3.
第一题是2
第2题也是2 第3题=3
用对数基本公式
1.10
2.题目错了中间 项由个2 答案为1
3.3 20=4*5 将题目化未lg2 和lg5
（因为我键盘问题过程省略了）
绛旓細2lg(5/3)-lg(7/4)+2lg3+(1/2)lg49 =lg(25/9)+lg9-(lg(7/4)-lg7)=lg25-lg(1/4)=lg(25*4)=lg100 =2.(lg2)^2+lg2lg5+lg50 =(lg2)^2+lg2lg5+lg5+lg10 =(lg2)^2+lg2lg5+lg5+1.=lg2*(lg2+lg5)+lg5+1 =lg2+lg5+1 =lg(2*5)+1 =2.lg(5^2)+2/...
绛旓細瑙ｏ細1.log1=logx (x),鍔爈ogx3=logx(3x)=f(x锛塯(x)=logx 4 褰<0x<1鏃讹紝f(x)>g(x锛夛紱褰1<x<4/3鏃讹紝g(x)>f(x);褰搙=4/3鏃讹紝f(x锛=g(x);褰搙>4/3鏃讹紝f(x)>g(x)2. 锛0锛1锛 鍖呮嫭1鍝︼紝鍙寰峰锛岄偅涓皬涓夎褰0鍗冲彲 3锛4锛屼笌1宸笉澶氾紝鍙鍒嗙被璁ㄨ灏卞彲浠ヤ簡...
绛旓細=(3+lg7/lg2)/(1+lg7/lg2)=(3+ab)/(1+ab)3銆佽В娉1锛15+8+14=37,澶9浜,9-3-3=3,娌℃湁浜哄悓鏃跺弬鍔犱笁椤规瘮璧,鎵浠ュ悓鏃跺弬鍔犵敯寰勫拰鐞冪被姣旇禌鐨勬湁3浜.娌℃湁浜哄悓鏃跺弬鍔犱笁椤规瘮璧,15浜哄弬鍔犳父娉虫瘮璧,鏈6浜轰袱椤癸紝鎵浠15-6=9锛屽彧鍙傚姞娓告吵涓椤规瘮璧涚殑鏈9浜 锛堣繖绉嶈В娉曠畝渚匡紝蹇熷皬鐚倝瑙ｆ硶锛夊彟瑙...
绛旓細1.a^m*a^n=a^(m+n),m+n=log a MN,m+n=log a MN,log a MN=m+n 2.log a MN=log a M+log a N log a M/N=log a M-log a N log a M^n=nlog a M log c a/log c b=(lga/lgc )/(lgb/lgc)=lga/lgb=log a b 3.log a xy/z=log a x+log a y-log a ...
绛旓細缁忔楠,x= 鏄師鏂圭▼鐨勮В, x=锛 涓嶅悎棰樻剰,鑸嶅幓.4銆佽В锛氬師鏂圭▼涓 锛6脳3-x锛27=0,鈭(3-x锛3)(3-x锛9)=0.鈭3-x锛3 0,鈭寸敱3-x锛9=0寰3-x=32.鏁厁=锛2鏄師鏂圭▼鐨勮В.5銆 瑙ｏ細鍘熸柟绋嬩负 =27,鈭-3x=7锛屾晠x=锛 涓哄師鏂圭▼鐨勮В.6銆佽В锛氭柟绋嬩袱杈瑰彇甯哥敤瀵规暟,寰楋細(x锛1)lg...
绛旓細甯哥敤瀵规暟:___浠10涓哄簳鏁扮殑瀵规暟___鑷劧瀵规暟:___浠涓哄簳鏁扮殑瀵规暟___4.瀵规暟涓庢寚鏁伴棿鐨勫叧绯:___浜掍负閫嗚繍绠梍__5.鍒ゆ柇:x=10g 2 (-2) ( 閿 )x=10g 2 0 ( 閿 )6.10g a a=___1___ 10g a 1___0___
绛旓細1.lg鏍瑰彿1.8=1/2lg1.8=1/2(lg18-lg10)=1/2(lg2+2lg3-1)=1/2(a+2b-1)2.log(鈭2)(鈭6+4鈭2-鈭6-4鈭2)=1/2log(鈭2)(鈭6+4鈭2-鈭6-4鈭2)^2 =1/2log(鈭2)锛8锛=3/2log(鈭2)锛2)=3
绛旓細1)lg25=2lg5 lg2*lg50 =lg2(2lg5+lg2)鍘熷紡=2lg5+2lg2lg5+2(lg2)^2 =2lg5+2(lg2+lg5)lg2 =2lg5+2lg2 =2lg10 =2 2)鈭歔(lg3)^2-lg9+1]=鈭歔(lg3)^2-2lg3+1]=鈭(lg3-1)^2 =1-lg3 lg鈭27 =(3/2)lg3 lg8 =3lg2 lg鈭1000 =(3/2)lg10 =(3/2)lg鈭...
绛旓細瑙ｏ細锛1锛夊師寮=[lg3+(2/5)(2lg3)+(3/5)(3lg3/2)-lg3/2]/(4lg3-3lg3) (搴旂敤瀵规暟鎹㈠簳鍏紡)=(11/5)lg3/(lg3)=11/5锛涳紙2锛夊師寮=[(2lg3)/(3lg2)]*[(5lg2)/(lg3)] (搴旂敤瀵规暟鎹㈠簳鍏紡)=10/3锛涳紙3锛夊師寮=(lg5+lg7)/lg5+lg2/(-lg2)+(2lg5+lg2)/lg5-...
绛旓細lg(x+2y)+lg(x-y)=lg2+lgx+lgy lg(x+2y)(x-y)=lg2xy (x+2y)(x-y)=2xy x^2+xy-2y^2=2xy x^2-xy-2y^2=0 (x-2y)(x+y)=0 x=2y,x=-y 鐢卞畾涔夊煙锛寈>0,y>0 鎵浠=-y涓嶆垚绔 鎵浠=2y x/y=2
