(log)
问题描述：
(log)
1.solve the following exponential equation (use log if necessary)
8(6^(2x+5))=7^(3x-4)
2.solve the following simultaneous equations.
log x = log (5y) -2 ------- (1)
log y - 3 log ((8x+3)^(1/3)) =0 ------- (2)
答
2.（2）→log y-log（8x+3）=0→y=8x+3
（1）→log x=log（40x+15）-2→log（ （40x+15）/x ）=2→（40x+15）/x=10^2→x=¼→y=5