2的m次方=5 求2的3m次方和2的3+m次方

问题描述:

2的m次方=5 求2的3m次方和2的3+m次方

2的m次方=2^m=5
2的3m次方=2^3m=(2^m)³=5³=125
2的3+m次方=2³×2^m=8×5=40

2^m=5
m =log5
2^(3m)
=2^(3log5)
=2^(log125)
=125
2^(3+m)
= (2^3).2^m
=8(5)
=40


由 2^m =5,可得
2^(3m) = (2^m)^3 = 5^3 = 125
2^(3+m) = 2^3×2^m = 8×5 =40

因为2的m次方=5
1) 2的3m次方实际是 (2的m次方)的3次方, 也就是5的3次方, 即125
2) 2的3+m次方等于2的3次方乘以2的m次方, 等于8*5, 即40

∵ 2 ^ m = 5
∴ 2 ^ 3 m
= (2 ^ m)³
= 5 ³
= 125
2 ^ (m + 3)
= 2 ^ m · 2 ³
= 5 × 8
= 40