Question 1137995
Jeez.
less than 1 second to think of 3*7 = 21
Like a flash card.
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Find factors of 21 that differ by 4
21 = 1*21   NG
21 = 3*7  That's it.
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The other tutor made a quadratic equation, then factored it, finding the same 2 factors, 3 & 7.
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If the solution was not integers, it would be different. but WAKE UP.