Given:
F(x)=∫0xt⋅f(t)dt
Now, applying Newton Leibnitz Theorem we get,
F′(x)=x⋅f(x)
And F(x2)=x4+x5
Let x2=t
⇒F(t)=t2+t25
⇒F′(t)=2t+25t23 asF′(x)=x⋅f(x)
⇒t⋅f(t)=2t+25t23
⇒f(t)=2+25t21
⇒r=1∑12f(r2)=r=1∑122+25r
⇒r=1∑12f(r2)=24+25[212(13)]
⇒r=1∑12f(r2)=219