LilVeroDez13
Counterexample problem.. jus want to know if its right. Thanks!



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LilVeroDez13
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x = 1

Emah
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that looks right:)

LilVeroDez13
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thanks! :)

TuringTest
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it's not right

TuringTest
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what would happen if you plugged in x=1 ?
you get\[x^2\ge1\implies x\ge1\]\[1^2\ge1\implies1\ge1\]where is the falsehood here?

myininaya
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I agree with @TuringTest 1 does equal 1.

LilVeroDez13
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ohh yeah.. it wouldnt b false.

Emah
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but its saying OR equal to

TuringTest
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and it is equal, so it's true

LilVeroDez13
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@Emah yeahh thats true.. i dont see another answer that works

TuringTest
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try each one individually

Emah
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oh oops i sdidnt see the part that said couterexample:( sorry

LilVeroDez13
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ohh its okk

TuringTest
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what do you get when you plug in x=2\[x^2\ge1\]\[x\ge1\]are both still true?

LilVeroDez13
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i get that its false

TuringTest
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which part is false?

LilVeroDez13
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first part

TuringTest
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\[2^2\ge1\]is not true you say?

LilVeroDez13
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Im confused

TuringTest
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we need to find an example where the first part is true, and the second part is false to disprove the statement

TuringTest
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\[2^2=4\]and four is greater than one, so \[x^2\ge1\]is true for x=2

TuringTest
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what about the other part, is\[2\ge1\]?

LilVeroDez13
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its true because 2 is greater tha 1

TuringTest
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right, so both statements are true for x=2, so this is not a counterexample

TuringTest
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what about for x=3
is\[x^2\ge1\]and is\[x\ge1\]?

LilVeroDez13
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first one is 9 > 1 (true)
second one is 3 > 1 (true too)

LilVeroDez13
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so than its 1/4 (: