Solving System of Equations with Variables

[enibaraliu]

1st: 3^2x-2y+2*3^x-y-3=0
3^x+3^1-y=4


2nd: 3^y*$$\sqrt[x]{64}$$=36
5^y*$$\sqrt[x]{512}$$=200

3rd: 9*5^x+7*2^x+y=457
6*5^x-14*2^x+2=-890

At first i treid to replace 3^x with u , 3^x=u and 3^y=v but I don't know what to do then.

At 2nd, $$\sqrt[x]{64}$$ I replace with 2^6/x but then this be more complicate,and I don't know another way,please help me!

 

[happyg1]

For 1,
Cant you solve the second equation for $$3^x$$ and then plug it back into the first one after you break it down using your exponent properties?

that's just suggestion at first glance.
CC