CPM Homework Help : CAAC Problem 2-31

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Home > CAAC > Chapter 2 > Lesson 2.1.3 > Problem 2-31

2-31.

Decide if each statement below is true or false. Explain how you know and name any properties you use.

$-19+7=-7+19$
Hint (a):
Solve each side of the equation. Are they equal?
Answer (a):
This statement is false, because $-12\ne12$ .

$\frac { 4 } { 5 } \cdot 1 = \frac { 4 } { 5 }$
Hint (b):
Try using the Identity Property of Multiplication.
What does this property tell you about this statement?

$\frac { 3 } { 2 } \cdot \frac { 2 } { 3 } = 1$
Hint (c):
Do you remember what a multiplicative inverse is?
If not, refresh your memory using the glossary before approaching this problem.

$5\cdot7-5\cdot\frac{1}{5}=34$
Step 1 (d):
Simplify any terms with multiplication.
$(5)(7)-5\left(\frac{1}{5}\right)$
$35-1$
Step 2 (d):
Combine using subtraction, and then compare this value to $34$ .
Answer (d):
This statement is true, since $34=34$ .

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