we know that in a biquadratic eqn.

since all roots r real by descartes rules of signs

a⁵+b⁵+c⁵+d⁵=5pq in the general eqn. of 4th degree where a,b,c,d r the roots.

a⁵+b⁵+c⁵+d⁵=-105

hope u got it..