The number x is a solution to the equation 5x^2 + 4 = 3x + 9. What is the value of (10x-3)^2?

So using the quadratic formula we get

what I'm confused about is the fact that it asks for one solution and that is not possible with the plus-minus sign. Can anybody help? Thanks

\(x = {3 \pm \sqrt{109} \over 10}\)

Guest Feb 12, 2022