If $$ {\sqrt{2x+9}+x=13}$$ then find the value of x?

If $$ {x^4}+{1\over{x^4}}$$ then find $$ {x^3}-{1\over{x^3}}=?$$

If $$ ({x+y\over z})=2$$ , then what is the value of $$ [{ {y\over {y-z}}}] +[{ {x\over {x-z}}}]$$.

If (27x³ – 343y³) ÷ (3x – 7y) = Ax² +By² + 7Cyx, then the value of (4A – B +5C) is:

If a, b are rational number and (a-1)√2+3=b√2+a, the value of (a+b) is : 

If $$ {x+{1\over x}}=2$$ then find out the value of $${2x^2+2}\over{3x^2+5x+3}$$

simplify the following equation
$$ (1-{1\over3})(1-{1\over4})(1-{1\over5})......(1-{1\over n})$$

If 5^√x + 12^√x = 13^√x, then x is equal to: