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Find the product of all positive integer values of $c$ such that $8x^2+15x+c=0$ has two real roots.

 Feb 21, 2021
 #1
avatar+1223 
0

The discriminant needs to be greater than 0.

 

\(\Delta = b^2- 4ac = 225 - 32c > 0\)

 

\(c < \frac{225}{32}\)

 

225/32 is equal to 7.03125, so c can be any integer from 1 to 7. The sum is 28.

 Feb 21, 2021
 #2
avatar+206 
-1

Actually, it's 5040 because the question says product not sum.

 Feb 21, 2021

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