1.已知,3x(x^n+5)=3x^n+1+45,求x的值．2.若1＋2＋3＋…＋n＝a,求代数式(x^n*y)(x^n-1*y&_数学解答

1.已知,3x(x^n+5)=3x^n+1+45,求x的值．
2.若1＋2＋3＋…＋n＝a,求代数式(x^n*y)(x^n-1*y²)(x^n-2*y³)...(x²y^n-1)(xy^n)的值.
3.已知2x＋5y－3＝0,求4^x*32^y的值.
4.已知25^m*2*10^n=5^7*2^4,求m、n．
5.已知a^x=5,a^(x+y)=25,求a^x+a^y的值.

人气：292 ℃　时间：2020-01-26 06:41:30

解答

(1)(3x^n+1)+15x=(3x^n+1)+45
15x=45
x=3
(3)2x+5y=3
4^xX32^y=2^2xX2^5y=2^2x+5y=2^3=8
(4)25^mX2X10^n=5^2nX2X2^nX5^n=5^2m+nX2^n+1
2m+n=7
n+1=4
n=3
m=2
(5)a^(x+y)=a^xXa^y=5Xa^y
a^y=5
a^x+a^y=5+5=10