[log5(2)*log7(9)]/[log5(3)*log7(4)] [log5(2)*log7(9)]/[log5(3)*log7(4)]
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/29 09:34:54
[log5(2)*log7(9)]/[log5(3)*log7(4)] [log5(2)*log7(9)]/[log5(3)*log7(4)]
[log5(2)*log7(9)]/[log5(3)*log7(4)]
[log5(2)*log7(9)]/[log5(3)*log7(4)]
[log5(2)*log7(9)]/[log5(3)*log7(4)] [log5(2)*log7(9)]/[log5(3)*log7(4)]
用换底公式
[log5(2)*log7(9)]/[log5(3)*log7(4)]
=[lg2/lg5*lg9/lg7]/[lg3/lg5*lg4/lg7]
=[lg2*lg9]/[lg3*lg4]
=1
log里面的指数可以提取出来 如log5(2)=2log5 这个是基本运算公式; 原式就化为2*9/(3*4)=3/2 (log部分约去了 )