1.若2x+5y=4 求4^x乘以32^y

题目

1.若2x+5y=4 求4^x乘以32^y
2.已知5乘以25^x乘以125^x=5^21 求x^3

答案

1.若2x+5y=4 求4^x乘以32^y
4^x * 32^y =(2^2)^x*(2^5)^y=2^(2x+5y)=2^4=16
2.已知5乘以25^x乘以125^x=5^21 求x^3
25^x^125^x=(5^2)^x*(5^3)^x=5^(2x+3x)=5^21=>x=21/5
x^3=(21/5)^3=74.088