2.4 Properties from Algebra and Proofs
20. If x + y = 9 and x - y = 12, then 2x = 21.
ADDITION
21. If AB - CD = EF - CD, then AB = EF.
ADDITION
14. If 1/2 m. angle F = 1/2 measure angle G, then m. angle F = m. angle G.
DIVISION
22c. x = -12
DIVISION
SET 22 and 24, TWO-Column Proof: Answer each question as in 19-21. Given the STATEMENT, what is the the REASON? If the statement comes from the Given statements for the problem, then the reason is "Given". Think of the next statement, (for example 2b.)as the conclusion from the hypothesis 2a, and the reason is written together with the statement in 2b. Thus, for #22, the REASON why 2/3 x = -8 is because BOTH sides was MULTIPLIED by 3. 22a. 2/3 x = -8GIVEN
GIVEN
22b. STATEMENT: 2x = -24
MULTIPLICATION
17. m angle A = m angle A
REFLEXIVE
13. If y = 2x + 3 and x = 2, then y = 7
SUBSTITUTION
16. If m. angle A = 90 and m. angle B = 90 then m angle A = m angle B.
SUBSTITUTION
#s 12 to 21, NAME the PROPERTY (write ONLY the name, so don't type "property of equality":)
SUBTRACTION
19. If AB + BC = 12, then BC = 12 - AB.
SUBTRACTION
18, If m angle 1 = m angle 2, m angle 1 = m angle 2.
SYMMETRIC
15. If AB + BC = AC and AC = EF + GH, then AB + BC = EF + GH.
TRANSITIVE
