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2-3 Conditional Statements. Ms. Andrejko. Real Life. If you would like to speak to a representative press 0 now. Vocabulary . Conditional Statement- a statement that can be written in if-then form If-then statement- is of the form if p , then q
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2-3 Conditional Statements Ms. Andrejko
Real Life If you would like to speak to a representative press 0 now
Vocabulary • Conditional Statement- a statement that can be written in if-then form • If-then statement- is of the form if p, then q • Hypothesis- the phrase immediately following the word if • Conclusion- the phrase immediately following the word then • Related Conditionals- other statements that are based on a given conditional statement • Logically equivalent- Statements with the same truth values
Notation pq= if p, then q p= hypothesis q= conclusion
Examples • Identify the hypothesis and conclusion: • If 3x+4=-5, then x=-3 • If you take a class in television broadcasting, then you will film a sporting event Hypothesis: 3x+4=-5 Conclusion: x=-3 Hypothesis: Take a class in television broadcasting Conclusion: Film a sporting event
Practice • Identify the hypothesis and conclusion: • If you purchase a computer and don’t like it, then you can return it within 30 days. • If x+8 = 4, then x= - 4 Hypothesis: purchase a computer and don’t like it Conclusion: return it within 30 days Hypothesis: x+8=4 Conclusion: x= -4
Examples • Write each statement in if-then form: • Those who do not remember the past are condemned to repeat it. • Adjacent angles share a common vertex and a common side IF you do not remember the past, THEN you are condemned to repeat it. IF 2 angles are adjacent, THEN they share a common vertex and common side.
Practice • Write each statement in if-then form: • A polygon with four sides is a quadrilateral. • An acute angle has a measure less than 90. IF a polygon has four sides, THEN it is a quadrilateral IF an angle is acute, THEN its measure is less than 90.
Examples • Determine the truth vale of the following conditionals: • If a and b are negative, then a + b is also negative. • If you have five dollars, then you have five one-dollar bills. T T = T T F = F Counterexample: you have 1, $5 bill.
Practice • Determine the truth vale of the following conditionals: • If two angles are supplementary, then one of the angles is acute. • If I roll two six-sided dice and sum of the numbers is 11, then one die must be a five. T F = F Counterexample: 90° and 90° - neither are acute T T = T 5+6 = 11
FOLDABLE INSIDE CONDITIONAL TAB Hypothesis Conclusion If-Then Statement
Vocabulary qp • Converse- formed by exchanging the hypothesis and conclusion • Inverse- formed by negating the hypothesis and conclusion of the conditional • Contrapositive- formed by negating the hypothesis and conclusion of the converse ~p ~q ~q ~p
IMPORTANT NOTE **** NOTE: • The conditional and it’s contrapositiveare logically equivalent • The converse and inverse are logically equivalent
Examples • Write the converse, inverse, and contrapositive of each statement: • If 89 is divisible by 2, then 89 is an even number • If an animal is a lion, then it is a cat that can roar Converse: If 89 is an even number, then 89 is divisible by 2. Inverse: If 89 is not an even number, then 89 is not divisible by 2. Contrapositive: If 89 is not an even number, then 89 is not divisible by 2. Converse: If an animal is a cat that can roar, then it is a lion. Inverse: If an animal is not a lion, then it is not a cat that can roar. Contrapositive: If an animal is not a cat that can roar, then it is not a lion.
Examples • Write the converse, inverse, and contrapositive of each statement: • If you are 15 years old, then you are eligible to drive. • If the temperature is freezing, then precipitation falls as snow. Converse: If you are eligible to drive, then you are 15 years old. Inverse: If you are not 15 years old, then you are not eligible to drive. Contrapositive: If you are not eligible to drive, then you are not 15 years old. Converse: If precipitation falls as snow, then the temperature is freezing. Inverse: If the temperature isn’t freezing, then the precipitation does not fall as snow. Contrapositive: If precipitation doesn’t fall as snow, then the temperature isn’t freezing.
FOLDABLE INSIDE CONDITIONAL TAB Converse Inverse Contrapositive