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What number must be added to both sides of the equation in order to complete the​ square? Please someone help..

x^2+3x=-3

 Oct 22, 2020
 #1
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You want

(x + c)2 = k

 

Expand the left-hand side

 

x2 + 2cx +  c2 = k

 

Compare each term with

x2 + 3x = -3

 

Clearly we need 2c = 3,  so c = 3/2.  That means we must add c2 = 9/4 to each side (so k = -3 + 9/4 = -3/4)

 

(x + 3/2)2 = -3/4

 Oct 22, 2020

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