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Use the completing the square method to solve the following. Round the solutions to the nearest tenth place.

 

1. n= 18n + 40

 

 

 

2. 6x2 - 48 = -12x 

 Mar 16, 2018
 #1
avatar+18458 
+2

1)  n^2 -18n  = 40      take 1/2 of the 'n' coefficient, square it , then add it ro both the sides of the equation

 

n^2 -18n + 81 = 40  + 81

(n-9)^2     = 121                        Now take sqrt of both sides

(n-9) = +- 11

n=20  or  -2

 Mar 16, 2018
 #2
avatar+18458 
+1

2) similar here

6x^2 +12x = 48

 

BUT you need to have x^2 coefficient = 1    so divide through by 6

x^2 + 2x = 8      Now 'complete the square' again

 

x^2 + 2x +1 = 8+1

(x+1)^2  =  9

x + 1    = +- 9

x =8 or -10

 Mar 16, 2018

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