Question 412387
0 = -2q^2 + 820q - 8000

divide both sides by -1
0=2q^2-820q+8000
/2
q^2-410+4000=0
...
q^2-400q-10q+4000=0
(split the middle term into two terms such that their sum is -410 and product is 4000)
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q(q-400)-10(q-400)=0
(q-400)(q-10)=0

q=400 OR q=10