ParthKohli
Solve \(x(x + 3) = -9\) NOT by the quadratic formula.
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PeterPan
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Well, clearly x cannot be positive, as that would mean x+3 is positive too.
x must be negative, but no less than -3, or else x+3 would also be negative.
ParthKohli
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Complex numbers?
ParthKohli
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I know them by the quadratic formula
PeterPan
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maybe?
PeterPan
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Oh, right. I forgot to assume the real-ness of x...
I'm lost :D
phi
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you can complete the square as an alternative to the quadratric formula
PeterPan
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That's kinda like using the quadratic formula anyway? :D
phi
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you will get complex roots
ParthKohli
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Well\[x^2 + 3x + 2.75 = -9 + 2.75\]
PeterPan
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What's with the 2.75?
You mean 2.25, right?
ParthKohli
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Yes, whoops
sami-21
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can i use compeleting square ??? or factor mehod ?
ParthKohli
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\[(x + 1.5)^2 = -9 + 2.25\]Yes, I wanna know how to factor this over \(\mathbb C\) without knowing the roots!
PeterPan
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It seems like it's already almost done?
sami-21
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well, i guess this is a good condidate for completing square .
ParthKohli
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OK, completing the square worked out well. Thanks @phi :-)