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Mathematics 7 Online
OpenStudy (anonymous):

Let x ∈ R. If x^2 - 2x + 2 ≤ 0, then x^3 ≥ 8. Prove that this implication is either true or false. @satellite73 @ganeshie8 @myininaya @UnkleRhaukus @zepdrix @RadEn @robtobey @Luigi0210 @primeralph @shamil98 @Compassionate @nincompoop @Preetha @Euler271 @Kainui @ehuman @wolfe8 @wolf1728 @Yttrium @zpupster @tester97 @emilyhaddad @Lena772 @nikato @sarah786 @Kristen17 @AustinC @kittiwitti1 @adrynicoleb @doggy @lilai3 @thadyoung @lucaz @TheForbiddenFollower @linh412986 @comf@UH60blackhawk @BlackLabel @leozap1 @ComeAlongP0nd @CrayolaCrayon_ @grinnell.12 @David. @lovelycharm @adrynicoleb @Cutefriendz

OpenStudy (tester97):

this is considered a mass tagging and consider this annoying. please refrain from this in the future. thank you.

ganeshie8 (ganeshie8):

F -> something true

OpenStudy (anonymous):

Ops dunno ^^

OpenStudy (doggy):

Cellphone.

ganeshie8 (ganeshie8):

If x^2 - 2x + 2 ≤ 0, then x^3 ≥ 8. --------------- that part is false, cuz from the hypothesis, x is real, and we dont have any real values satisfying that part.

OpenStudy (anonymous):

So is the whole implication false or true?

ganeshie8 (ganeshie8):

F -> anything is true

ganeshie8 (ganeshie8):

if the premisis is False, the implication is true. so the whole implication is true.

OpenStudy (anonymous):

What were you trying to say in the previos comment then?

ganeshie8 (ganeshie8):

which comment ?

OpenStudy (anonymous):

If x^2 - 2x + 2 ≤ 0, then x^3 ≥ 8. --------------- that part is false, cuz from the hypothesis, x is real, and we dont have any real values satisfying that part.

OpenStudy (unklerhaukus):

completing the square on the in-equation in the antecedent, yields an in-equation that is necessarily false. An implication is true when either, •its antecedent and its consequent are both true, or •if the antecedent is false

OpenStudy (kainui):

@UnkleRhaukus I don't see how completing the square results in an inequation that's necessarily false.

OpenStudy (kainui):

Well actually, yes I do, I don't know why I'm saying that.

OpenStudy (anonymous):

If a statement is false, that it can imply any other statement. So x^2 - 2x + 2 ≤ 0, then x^3 ≥ 8 is true since x^2 - 2x + 2>0 so x^2 - 2x + 2 ≤ 0 is false.

OpenStudy (kainui):

|dw:1388648507577:dw|

OpenStudy (kainui):

Obviously an upwards shaped parabola that's raised 2 points off the x-axis isn't going to hit zero ever, so the antecedent is completely, totally, incredibly false.

OpenStudy (unklerhaukus):

\[x^2 - 2x + 2 \le 0\\ (x-1)^2+1\le0\\ (x-1)^2\le-1\] any real number squared is positive a positive number is never less than or equal to negative one

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