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# Math inequalities help watch

1. Gosh, okay this seems like a simple question but:

Attachment 728880

Why is the (2k) [outside the bracket] to the power of 2
2. Post it please so we can help.
3. (Original post by CorpusLuteum)
Gosh, okay this seems like a simple question but:

Why is the (2k) outside the bracket to the power of 2
4. I cannot see the attachment but you're asking why is 2k in bracket? Well, (x+2k)^2 when expanded will yield an extra (2k)^2 term which you don't, hence you subtract it.
5. (Original post by RDKGames)
Okay I think it worked now?
6. (Original post by CorpusLuteum)
Gosh, okay this seems like a simple question but:

Attachment 728880

Why is the (2k) outside the bracket to the power of 2
7. (Original post by CorpusLuteum)
Okay I think it worked now?
yes, it worked, now.

do you know how to complete the square?

Can you complete the square and solve

x^2 - 4x -1 = 0 ??
8. x^2+4kx-k = 0 --> (x+2k)^2-(2k)^2-k=0.

E.g. x^2+6x+10 --> (x+3)^2 - 3^2 + 10 --> (x+3)^2 + 1. It's how completing the square works; you generate an extra term that should be subtracted.
9. (Original post by CorpusLuteum)
Okay I think it worked now?
Because but you only want the first two terms, hence , but hence that's where it comes from.

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