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Published byAmber Golden Modified over 9 years ago
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From conclusions by applying the laws of logic
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Symbolic Notation Conditional statement If p, then qp ⟶q Converseq⟶p Biconditional p ⟷ q
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Let p be “the value of x is – 4” Let q be “ the square of x is 16” Write p ⟶q Write q⟶p
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Let p be “the value of x is – 4” Let q be “ the square of x is 16” Write p ⟶q If the value of x is – 4, then the square of x is 16 Write q⟶p If the square of x is 16, then the value of x is – 4 Is p⟷q True?
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Write the Contrapositive The negation of p “the value of x is -4” is written as ~p; meaning “the value of x is not -4” The contrapositive~q ⟶~p If the square of x is not 16, then the value of x is not -4. Is this true?
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The inverse would be ~p ⟶~q If the value of x is not – 4, then the square of x is not 16. Is this True? Which statements are true?
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The inverse would be ~p ⟶~q If the value of x is not – 4, then the square of x is not 16. Is this True? Which statements are true? The conditional statement and the contrapositive are both true. The converse and inverse are both false.
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Remember the conditional and the contrapositive are equivalent statement as are the converse and the inverse.
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Deductive Reasoning Deductive reasoning uses known facts, definitions and postulates to make a logical argument. Logical arguments follow laws and methods. Here are two laws of logical Law of Detachment and the Law of Syllogism.
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Law of Detachment If p ⟶ q is a true conditional, then p is true and q is true. Does p always have to be TRUE!
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Law of Detachment If p ⟶ q is a true conditional, then p is true and q is true. Does p always have to be TRUE! Yes
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Law of Syllogism Here we have a chain is true statements linked together. If p ⟶q and q⟶r, then p⟶r
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Law of Syllogism Here we have a chain is true statements linked together. If p ⟶q and q⟶r, then p⟶r. I go to school at Marian High school. Marian High school is in Mishawaka. I go to school in Mishawaka.
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Is the Law of Syllogism always right?
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Lets make some correct conclusion. If a fish swims at 68 mi/h, then it swims at 110 km/h. If a fish can swim at 110 km/h, then it is a sailfish
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More Facts If a fish is the largest species of fish, then it is a Great White Shark If a fish weights over 2000 lbs, then it is the largest species of fish.
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One more If a fish is the fastest species of fish, then it can reach speeds of 68 mi/h. What Conclusion can you make?
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Homework Page 91 – 93 #8 – 20 even 24 – 34 even, 45 - 48
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Homework Page 91 -93 #9 – 19 odd 23 – 35 odd 36 – 42 even, 49
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