If a0,a1,a2,a3 are all positive, then 4a0x3+3a1x2+2a2x+a3=0 has at least one root in (-1, 0) if
a0+a2=a1+a3 and 4a0+2a2>3a1+a3
4a0+2a2<3a1+a3
4a0+2a2=3a1+a3 and a0+a2<a1+a3
None of these
P(x)=4a0x3+3a1x2+2a2x+a3 is a polynomial, so it is continuous for all x
P(x)=0 has a root in (−1,0)P(−1)P(0)<0now, P(0)=a3>0⇒P(−1)=−4a0+3a1−2a2+a3<0⇒4a0+2a2>3a1+a3
Also using Rolle's theorem,Q(x)=∫p(x)dx=a0x4+a1x3+a2x2+a3x+aFor Q′(x)=p(x)=0for at least one root in
Q(−1)=Q(0)⇒ a0−a1+a2−a3+d=d or a0+a2=a1+a3