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teach me how to complete the square when the x^2 value is higher than 1 please

 Sep 17, 2016
 #1
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0

STUDY THIS EXAMPLE SLOWLY AND CAREFULLY:

 

Solve for x:
4 x^2-8 x = 0

Divide both sides by 4:
x^2-2 x = 0

Add 1 to both sides:
x^2-2 x+1 = 1

Write the left hand side as a square:
(x-1)^2 = 1

Take the square root of both sides:
x-1 = 1 or x-1 = -1

Add 1 to both sides:
x = 2 or x-1 = -1

Add 1 to both sides:
Answer: |x = 2 or x = 0

 Sep 17, 2016
 #2
avatar+129840 
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Here's a pretty good tutorial on this topic :

 

http://www.purplemath.com/modules/sqrquad.htm

 

 

 

cool cool cool

 Sep 17, 2016
 #3
avatar+37084 
+5

How about one like

3x^2 -10x +5 = 0   ?      Gets kinda messy, but it is done the same way.  DIvide thru by '3'

 

x^2 - 10/3 x = -5/3          Now take 1/2 of the 'x' term , square it and add to both sides

 

x^2 - 10/3 x  + 100/36  = -5/3  + 100/36      simplify

 

(x-10/6)^2  = 40/36     Take the sqrt of both sides

 

x- 10/6 = +- sqrt (40/36)

 

x =  10/6  +- sqrt40  / 6   = (10 +- sqrt40)/6

 Sep 17, 2016

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