All the roots of the equation a1z3+ a2z2+a3z+a4=3,where|ai|<=1,
i=1,2,3,4, lie outside the circle with centre origin and radius r: What is the value of r?
Textbooks often miss out to mention one thing in this problem and that is |z| < 1 condition. This condition will allow you to use infinite GP summation formula at appropriate point. Try to see if you are able to proceed further or send me a message (it can be done from the profile page) between 8.20 PM - 11 PM today and I will message you back with a virtual session link.