Ok, i've ALMOST got it... but W|A is balking at the final step.
Input[1]:
(1.0atm) = x(-(((0.2420[((atmdm^6)/(mol^2))])x)/(113097dm^3)^2) + (((77057.6)((dm^3atm)/(Kmol)))(298.2K))/((113097dm^3)-((2.6510^-2)((dm^3)/mol))x))
Output:
1 atm= x^2 ((298.2 K1 dm^3atm77058/(Kmol)*(per kelvin moles))/(113097 dm^3 (cubic decimeters)-0.142292 x 1 dm^3 (cubic decimeter) 1/mol (reciprocal mole))+x 1/mol^2 (per mole squared) 1 dm^6atm (decimeter to the 6 atmosphere) -1.892×10^-11/dm^6 (per decimeters to the 6))
Input[2]
solve for x; 1atm=[((298.2K(dm^3)atm77058/(Kmol))/(113097(dm^3)(-0.142292)(x)(dm^3)(1/mol))+(x(1/mol^2)(dm^6atm)-(1.892×10^-11/(dm^6)))(x^2)]
Output:
Wolfram|Alpha doesn't understand your query
Once more, I ask for help with getting input[2] to produce a value for x.
(also, once more, * does not mean italics in this context, ergo Kmol is not intended to mean kilo-mole, but Kelvin-Mole, as such. K=Kelvin)