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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. 

 

THANKS FOR ALL HHELP

 Jan 17, 2019
 #1
avatar+111329 
+2

8x^2 + 15x + c = 0

 

To have two real roots, the discriminant must be > 0

 

So

 

15^2 -  4*8*c > 0

 

225 > 32c

 

c < 225/32

 

c< floor [ 225/32]   

 

c < 7       but     also > 0 since c must be positive

 

So....the product of all positve c's =   7!  =   5040

 

 

cool cool cool

 Jan 17, 2019

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