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Find the constant $k$ such that the quadratic $2x^2 + 3x + k$ has a double root.

 Jun 11, 2020
 #1
avatar+21953 
0

To get a double root, you need the discriminant of the quadratic formula to be zero.

 

Discriminant:  b2 - 4·a·c

 

Quadratic:  2x2 + 3x + k     --->     a  =  2      b  =  3     c  =  k

 

--->     b2 - 4·a·c  =  0     --->     32 - 4·2·k  =  0     --->    9 - 8k  =  0

 

You'll need to solve this equation for k.

 Jun 11, 2020
 #2
avatar+1128 
+1

k=9/8

jimkey17  Jun 11, 2020

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