Lesson 2-5: Algebraic Proofs

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Presentation transcript:

Lesson 2-5: Algebraic Proofs Rigor – Use properties of equality, postulates, and definitions to justify steps in a proof. Relevance – logical thinking and proofs

Notes Highlight the properties on pg71 of the corebook Add the distributive property of equality to the list Distributive Property of Equality: a(b + c) = ab + bc

Example: Justifying single statements Symmetric Property of Congruence Distributive Property of Equality

Example: Justify each step used to solve for x. Think, what relationship do you see in the diagram? Definition: supplementary angles Substitution Property Combine like terms Subtraction property of equality Division property of equality

Example 2: Complete the proof Definition of a bisector Substitution Property Subtraction property of equality Division property of equality

Two – Column Proofs Format Statements First statement is always given info This side is for work No skipping steps Last line is ALWAYS what you are asked to find/prove Reasons First reason is ALWAYS GIVEN info (picture, words, definitions) Definitions, theorems, properties, formulas go here The last reason is NEVER “prove”

Back to the core book Turn to page 72 We will do practice problems 1 and 2 together

2-5 Classwork from the Core Book Pg 73 #4 – 8 Be ready to move on in 15 minutes You will be assigned 2-5 homework next week