a) x+231=5^{-53}
x+231=1/5^{53}
x=1/5^{-53}-231
b) x-7^{-42}=5^{4-57}
x-1/7^{42}=1/5^{53}
x-1/7^{42}=1/5^{53}
x=1/5^{53}+1/7^{42}
c) 6x/15+7^{10}=15^{26}
2x/5+7^{10}=15^{26}
2x=5*15^{26}-5*7^{10}
x= \frac{5*15^{26}}{2}-\frac{5*7^{10}}{2}
d) x-(145-12^{2})=625-220
x-145+144=405
x-1=405
x=406
e) 18/[(25-5x)*2-11]=2
18/(39-10x)=2
18=2(39-10x)
9=39-10x
10x=30
x=3
f) 2014-[2015-(2014-2013+x)]=2012
2014-(2014-x)=2012
2014-2014+x=2012
x=2012
Coroana?
