Short maths help,find the value of x,in it?

(y+1)/(y-1)=(-10)^(2x)

The negative base makes it very difficult to actually solve--in fact impossible. If we assume that it is instead ((-10)²)^x = 100^x, (which is technically the same thing), the we get something solvable:

(y + 1)/(y - 1) = 100^x
--> take the natural log of both sides

ln((y + 1)/(y - 1) = ln(1000^x)
-->

x * ln(100) = ln((y + 1)/(y - 1))
-->

x = ln((y + 1) / (y - 1)) / ln(100)

(y + 1) / (y - 1) = 100^x

log [ (y + 1) / (y - 1) ] = x log 100

log [ (y + 1) / (y - 1) ] = 2 x __________for log base 10

x = log [ (y + 1) / (y - 1) ] /2