Find the positive value of n such that the equation 9xˆ2+nx+1=0 has exactly one solution in x.

If you use the quadratic formula to solve for this quadratic....you will see that when the term

  sqrt(b^2-4ac)   is equal to ZERO , you will have only ONE x root

 

so   n^2 - 4(1)(9) = 0       Solve for n

        n^2 = 36

       n = 6