What are the solutions of the equation x^2-1=15

The ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years