x^2-x-20
Select the correct choice below.
(a) x^2-x-20=?
(b) The polynomial is prime.
x^2-x-20
Select the correct choice below.
(a) x^2-x-20=?
(b) The polynomial is prime.
Because a quadratic trinomial can have two solutions, x_{1} and x_{2, }it can ve factored in the following way
x^2 -x -20 = (x -x_{1})(x-x_{2}) (when the first coefficient in the trinomial is equal 1)
x1 and x2 are factors of -20 such that x1 +x2 = -(-1) =1. It is easy to see that x1 = 5, x2 = -4.
Thus, we have x^2 - x - 20 = (x-5)(x+4)