If 0.4 m + 0.8 n = 2.2 and 0.8 m + 0.4 n = 1.4, then the value of $$ {m^2}+{n^2}$$ is equal to 

If $$ {x+{1\over x}=\sqrt{3}}$$ then $$ {x^{48}+x^{378\over7}+x^{726\over11}+x^{60}}$$ is equal to

If $$ {8x\over{2x^{2}+7x-2}}=1, x>0,$$ then what is the value of of $$ {x^{3}+{1\over x^{3}}}$$ ?

If x – y + z = 15, xyz = -216 and xz – xy – yz = 18, then the value of $$ {x^3}-{y^3}+{z^3}=$$

Find the value of. 67²–33².

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

If $$ {x=a^{2\over3}-a^{-2\over3}}$$ then the value of $$ {x^{3}+3x}$$.

The ratio of two unequal sides of a rectangle is 1 : 2. If its perimeter is 24 cm, then the length of diagonal in cm is: