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Follow the process of completing the square to solve x2 - 10x + 8 = 0.
What is the value of the constant that will be isolated on the right side of the equation in step 3?

-32

-12

-8

 

Follow the process of completing the square to solve 2x2 + 8x - 12 = 0.
After adding B2 to both sides of the equation in step 4, what is the constant on the right side of the equation?

-32

112

160

 Jan 30, 2019
 #1
avatar+111357 
+1

x^2 - 10x + 8 = 0     subtract 8 from both sides

x^2 - 10x  = - 8       take 1/2 of 10 = 5....square it = 25    add to both sides

x^2 - 10x + 25 = - 8 + 25        factor the left and simplify

( x - 5)^2 = 17            take both roots

x - 5 = ±√17     add 5 to both sides

x = ±√(17) + 5

 

-8  was the isolated constant

 

 

2x^2  + 8x - 12 = 0       divide through by 2

x^2 + 4x - 6 = 0       add 6 to  both sides

x^2 + 4x  = 6          take 1/2 of 4 = 2.....square this = 4........add to both sides

x^2 + x + 4 =  6 + 4        factor the left and simplify

(x + 2)^2 = 10         take both roots

x + 2 = ±√10          subtract 2 from both sides

x = ±√(10)  - 2

 

 

 

cool cool cool

 Jan 30, 2019

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