已知27²=a^6=9^b,求2a²+2ab的值.已知：5^a=4,5^b=6,5^c=9 试说明2b=a+c

已知27²=a^6=9^b,求2a²+2ab的值.已知：5^a=4,5^b=6,5^c=9 试说明2b=a+c
已知27²=a^6=9^b,求2a²+2ab的值.已知：5^a=4,5^b=6,5^c=9 试说明2b=a+c

已知27²=a^6=9^b,求2a²+2ab的值.已知：5^a=4,5^b=6,5^c=9 试说明2b=a+c
27²=(3³)²=3^6
9^b=3^(2b)
a=3,b=3
2a²+2ab=2×3²+2×3×3=36
5^a=4,5^b=6,5^c=9
a=log5 4 ,b=log5 6 ,c=log5 9
2b=2log5 6=log5 36
a+c=log5 4+log5 9=log5(4×9)=log5 36
所以,2b=a+c

1、a^3=27,a=3
b=3
2、(5^b=6)^2=(5^a=4)*(5^c=9)
这样写能懂吧