The fraction x2+210x2−13x−3 is undefined when the denominator is equal to zero
then10x2−13x−3=0
by factorisation, 10x2−13x−3 = 0 becomes 10x2−15x+2x−3 = 0
5x(2x−3)+1(2x−3)=0
(5x+1)(2x−3)=0
then,x=−15 or 32