The coefficients a,b and  c of the quadratic equation ax2+bx+c=0,  are obtained by throwing a dice three times. The probability that this equation has equal roots is:

Given quadratic equation ax2+bx+c=0 has equal roots Δ=0  b24=acn(S)=63=216,a,b,c∈SSuppoe E be the event of getting a, b, c such that b24=ac E=2,1,1,4,2,2,4,4,1,4,1,4,6,3,3  Req probability =5216