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# Completing the square problem watch

1. im supposed to complete the square for 4x^2 - 12x + 15

the answer is (2x - 3)^2 + 6, but im not sure how they got there. 15 isn't a factor of 4, so I'm having trouble with taking it out :<

what do i do tsr what do i do
2. (Original post by frostyy)
im supposed to complete the square for 4x^2 - 12x + 15

the answer is (2x - 3)^2 + 6, but im not sure how they got there. 15 isn't a factor of 4, so I'm having trouble with taking it out :<

what do i do tsr what do i do
Forget about the 15, pretend it's not there:
3. (Original post by frostyy)
im supposed to complete the square for 4x^2 - 12x + 15

the answer is (2x - 3)^2 + 6, but im not sure how they got there. 15 isn't a factor of 4, so I'm having trouble with taking it out :<

what do i do tsr what do i do
As an alternative, you can use the most powerful trick in mathematics - substitution:

Note that and let so that

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Updated: March 28, 2016
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