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I easily can guess: the roots 2 and 4 gives the product of 8 (the constant term) and the difference of 2.
Their sum is 6, which should be " q", according to Vieta's theorem.
So, the answer is q = 6, based on my guessing.
Let's look what the Algebra solution will give us.
Let x and (x-2) are the roots.
Then their product is 8:
x*(x-2) = 8
x^2 - 2x - 8 = 0
(x-4)*(x+2) = 0.
So, there are 2 roots: x= 4 and x= -2.
The value x= 4 gives that two roots 4 and 2 which I guessed above, with the value of q= 6.
The value x= -2 gives two roots -2 and -4, with the value of q = -6.
So, the problem has two answers: q= 6 and q= -6. (Third line of the answers' choice)
Thus Algebra solution helped me to find 2 answers to the problem question: more than I could guess (!)