The set of values of for which the equation has all its roots real is given by

MATHEMATICS · Numerical · A Level · Mathematics · Algebra and Functions · Algebra and Functions

Problem

The set of values of

a

for which the equation

x^4+4x^3+ax^2+4x+1=0

has all its roots real is given by

(a_1,a_2]\cup\{a_3\}

. Then

|a_3+a_2|