When asked these kinds of problems you find the discriminate and use that to tell if you have one , two or zero real solutions.
The formula for the discriminate is b^2 - 4ac. I hope that looks familiar because it is the inside part of the quadratic formula. (the part under the radical)
so if your answer is greater than zero you have two solutions
if your answer is equal to zero you have one solution
if your answer is less than zero you have no real solutions it will be a complex solution.
So lets apply all that to your question:
5^2 - 4(1)(7) = -3
so your answer would be B no real-number solution.
