McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
Study Guide and Review
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Exercise 15 Page 324

How do you justify each steps you usually use to solve an equation?

Statements
Reasons
a. 6(x-4)=42
a. Given
b. 6x-24=42
b. Distributive Property
c. 6x=66
c. Addition Property of Equality
d. x=11
d. Division Property of Equality
Practice makes perfect

We have been given a two-column proof to complete.

Blank a.

We will start our proof with the given equation. a.&6(x-4)=42 a.&Given

Blank b.

We can justify each step to rewrite 6(x-4) as 6x-24 on the left hand side of the equation using the Distributive Property.

a(b+c)=ab+ac After rewriting (x-4) as (x+(- 4)), we can use the Distributive Property with a=6, b=x, and c=-4. We also need to notice that 6(- 4)=- 24, and that 6x+(- 24)=6x-24. b.&6x-24=42 b.&Distributive Property

Blank c.

According to the Addition Property of Equality, we can add a number to both sides of an equation. Ifa=b, thena+c=b+c In this case we add c=24 to both sides of the equation and use that 6x-24+24=6x and 42+24=66. c.&6x=66 c.&Addition Property of Equality

Blank d.

According to the Division Property of Equality, we can divide an equation by a nonzero number. Ifa=b and c≠ 0, thena/c=b/c In this case, we divide the equation by c=6 and use that 6x6=x and 666=11. d.&x=11 d.&Division Property of Equality

Completed Proof

Given:& 6(x-4)=42 Prove:& x=11 Proof:

Statements
Reasons
a. 6(x-4)=42
a. Given
b. 6x-24=42
b. Distributive Property
c. 6x=66
c. Addition Property of Equality
d. x=11
d. Division Property of Equality