Find the limit? How to calculate this limit ? 
$$\lim _{x\to 1}\frac{\sqrt{x^2-1}}{\sqrt[3]{x-1}}$$
An image for clarification.

$$\lim _{ x\rightarrow 1 }{ \left( \frac { \sqrt { { x }^{ 2 }-1 }  }{ \sqrt [ 3 ]{ x-1 }  }  \right) = } \lim _{ x\rightarrow 1 }{ \left( \sqrt [ 6 ]{ \frac { { \left( { x }^{ 2 }-1 \right)  }^{ 3 } }{ { \left( x-1 \right)  }^{ 2 } }  }  \right) = } \lim _{ x\rightarrow 1 }{ \left( \sqrt [ 6 ]{ \frac { { \left( { x }-1 \right) ^{ 3 }\left( { x }+1 \right)  }^{ 3 } }{ { \left( x-1 \right)  }^{ 2 } }  }  \right) = } \lim _{ x\rightarrow 1 }{ \left( \sqrt [ 6 ]{ \left( { x }-1 \right) \left( { x }+1 \right) ^{ 3 } }  \right) =0 } $$
