If the roots of the equation x3−9x2+23x−15=0 are in A.P then common difference of  that A.P is

The given equation is x3−9x2+23x−15=0 Given that roots are in A.P.,∴  the roots are (a−d),a,(a+d) Sum of the roots: (a−d)+a+(a+d)=9 ⇒3a=9 ∴  a=3 Product of the roots : (a−d). a.(a+d)=15 ⇒a(a2−d2)=15                        (∵    a=3) ⇒d=2