If $$ {P={96\over95×97}},{Q={97\over96×98}}$$ and $$ {R={1\over97}}$$ then which of the following is True?

(x+2y) (x² + 4y² – 2xy) equal to- 

If a =500, b=502 and c=504, then the value of a³ +b³ +c³-3abc

If a²+b²+c² = 2(a – b – c) – 3 then the value of 4a – 3b + 5c is 

If (a-b)=-3 , (b-c)=5 and (c-a)=-2, then the value of $$ {a^{3}+b^{3}+c^{3}-3abc\over a+b+c}$$.

$${3x+4y-2z+9=17},{7x+2y+11z+8=23}$$ and $$ {5x+9y+6z-4=18}$$ then what is  the value of $$ {x+y+z-34}$$?

If x²+y²-4x-4y+8=0, then the value of x-y is: 

If x = b+c -2a, y=c+a-2b, z=a+b-2c, then the value of x²+y²-z²+2xy is :