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

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

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

If $$ x=\sqrt{\sqrt{5}+1\over {\sqrt{5}-1}}$$ then the value  of $$ {5x^2-5x-1}$$ will be:

Two numbers x and y (x>y) such that their sum is equal to three times their difference. Then value of $$3xy\over 2(x^2-y^2$$ will be 

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

If $$ {x^2} -4x-1 $$ then the value of $$ {{x^6} -{x^4}+{x^2}-1}\over {x^3}$$ will be

If $$ {x^{12}+x^{3}\over {x^{6}}}=0$$ find $$ {x^{36}+{1\over x^{36}}}$$