If f(x)=x3+px2+qx+6, p,q,ϵR, f′(x)<0 for largest possible interval [−53,−1], then p2+q2=
141
27
41
37
f′(x)=3x2+2px+q<0, x∈[−53,−1]
∴3x2+2px+q=(x+1)(3x+5)
∴p=4, q=5
⇒p2+q2=42+52=16+25=41