log2^3=a,3^b=7,a、b表示log12^56
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/08/26 08:57:22
log2^3=a,3^b=7,a、b表示log12^56
log2^3=a,则lg3/lg2=a
lg3=alg2
3^b=7,则log3^7=b
lg7/lg3=b
lg7=blg3=ablg2
log12^56=lg56/lg12
=(lg7+lg8)/(lg3+lg4)
=(lg7+3lg2)/(lg3+2lg2)
=(ablg2+3lg2)/(alg2+2lg2)
=(ab+3)/(a+2)
再问: =(ablg2+3lg2)/(alg2+2lg2) =(ab+3)/(a+2) 怎么变哒
再答: lg7=blg3=ablg2 lg3=alg2 我前面解出来了啊,代入=(lg7+3lg2)/(lg3+2lg2) 不就是=(ablg2+3lg2)/(alg2+2lg2)吗? =(ablg2+3lg2)/(alg2+2lg2) =[(ab+3)lg2]/[(a+2)lg2] =(ab+3)/(a+2)【分子分母都有lg2,约去】
lg3=alg2
3^b=7,则log3^7=b
lg7/lg3=b
lg7=blg3=ablg2
log12^56=lg56/lg12
=(lg7+lg8)/(lg3+lg4)
=(lg7+3lg2)/(lg3+2lg2)
=(ablg2+3lg2)/(alg2+2lg2)
=(ab+3)/(a+2)
再问: =(ablg2+3lg2)/(alg2+2lg2) =(ab+3)/(a+2) 怎么变哒
再答: lg7=blg3=ablg2 lg3=alg2 我前面解出来了啊,代入=(lg7+3lg2)/(lg3+2lg2) 不就是=(ablg2+3lg2)/(alg2+2lg2)吗? =(ablg2+3lg2)/(alg2+2lg2) =[(ab+3)lg2]/[(a+2)lg2] =(ab+3)/(a+2)【分子分母都有lg2,约去】
log2^3=a,3^b=7,a、b表示log12^56
已知log2 3=a,log3 7=b,试用a,b表示log12 56
已知log2(3)=a,2^b=7,试用a,b表示log12(56)
已知log2(底数)3=a,3^b=7,用a.b表示log12(底数)56
已知log2'3=a,2的b次方=7,用a,b表示log12'56
已知lg2 =a ,lg3=b 求lg5,log2 3,log12 25用a,b表示
已知log2 3=a,3^b=7,求log12 56.
log2(3)=a,log3(7)=b.log12(56)=log3(7*8)=log3(7)+3log3(2)
换底公式运用已知log2 3=a,log3 4=b用a,b表示log12 16(请写出详细过程)
(1)已知lg 2=a,lg 3=b,试用a,b表示log12 5 (2)已知log2 3=a,log3 7=b试用a,
已知log10 2=a,log10 3=b,试用a、b表示log12 5
若log2 3=a,用a表示log12 3=_______