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# Help with solving x by completing the square Watch

1. 4x2 + 8x - 1
=> 4 [ x2 + 2x ] - 1
=> 4 [ (x + 1) 2 - 1 ] - 1
=> 4 (x + 1) 2 - (8/32) - (4/4)
=> 4 (x + 1) 2 - (3/4)

What's my next step from here?
2. (Original post by ℓove)
4x2 + 8x - 1
=> 4 [ x2 + 2x ] - 1
=> 4 [ (x + 1) 2 - 1 ] - 1
=> 4 (x + 1) 2 - (8/32) - (4/4)
=> 4 (x - 1) 2 - (3/4)

What's my next step from here?
Two things;

=> 4 (x + 1) 2 - (8/32) - (4/4) - this line isnt correct, look at how you multiplied the bracket above this line through by 4

=> 4 (x - 1) 2 - (3/4) - here inside the bracket has changed from (x+1) to (x-1), maybe this is just a typo though.
3. (Original post by DylanJ42)
Two things;

=> 4 (x + 1) 2 - (8/32) - (4/4) - this line isnt correct, look at how you multiplied the bracket above this line through by 4

=> 4 (x - 1) 2 - (3/4) - here inside the bracket has changed from (x+1) to (x-1), maybe this is just a typo though.
Ohh it's -5/4, and yeah the other one was a typo.

What do I do now?
4. (Original post by ℓove)
Ohh it's -5/4, and yeah the other one was a typo.

What do I do now?
huh? are you meaning to write

if you wanted to write it without the big brackets it would be

After that youre done if youve just been asked to complete the sqaure

Edit: oh solve for x, just difference of two squares from here -
5. (Original post by DylanJ42)
huh? are you meaning to write

if you wanted to write it without the big brackets it would be

After that youre done if youve just been asked to complete the sqaure

Edit: oh solve for x, just difference of two squares from here -
Thanks I got it!!!

Updated: October 13, 2016
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