Question

if d=a²+b²+c² and a, b, c, d are in ap then a+b+c+d

Answer 1

If they are in ap then b=(a+c)/2 2b^2=a^2+c^2+2ac 2c^2=b^2+d^2+2bd a+(a+c)/2+c +√(2c^2-b^2-2bd)