If  $$ \ {xy\over x+y}= a, $$ $${xz\over x+z}=b $$ and $$ {yz\over y+z} =c $$  where a, b, c are all non – zero numbers, then x equals to

A complete factorization of x⁴+64 is 

If p³ – q³ = (p-q)[(p-q)²+xpq)] then the value of x is

If $$x+{1\over x}=c{1\over c}$$ then the value of x

If P = 99, then the value of P(P²+3P+3) is

When a number x is divided by a divisor it is seen that the divisor = 4 times the quotient=double the remainder. If the remainder is 80 then the value of x is

If $${x}^2+{y}^2x+1=0$$ then the value of $$x^{31}+y{35}$$ is

 $${a\over b}={2\over3}$$ and $${b\over c}={4\over5}$$ then the ratio  $${a+b}\over {b+c}$$ equal to: