The x intrercepts is where the function crosses the x axis; In other words, it is where the output of the function is 0.
In a quadratic, you can start by factoring, if it’s unable to be factored then use the quadratic formula. Also, it is good to use the discriminate.
D= Discrimminate
D>0 2 real solutions
D=0 1 real solution
D<0 2 imaginary solutions.
The discrimminate is the equation/expression under the radical of the quadratic formula. With this formula, it’s not factorable. Using the discriminate it is also seen, as you’ll get a negative in the square root. This is imagenary because you cannot take the root of a negative value, which is why “i” is used to represent the square root of negative one.