JEE Main 202131 Aug, Morning shiftMathematicsMediumLimit, Continuity and Differentiability420× since 2002
If 'R' is the least value of 'a' such that the function f(x) = x² + ax + 1 is increasing on [1, 2] and 'S' is the greatest value of 'a' such that the function f(x) = x² + ax + 1 is decreasing on [1, 2], then
the value of |R S| is ___________.