counterexamples

If it is a fraction, then it is a number between zero and one. What is an appropriate counterexample?

• 2/3
• 4/5
• 1/2
• 3/2

Tags

CCSS.6.NS.C.7A

CCSS.6.NS.C.7B

If it is an angle, then it is acute. What is an appropriate counterexample?

• 70⁰
• 45⁰
• 120⁰
• True. There is no counterexample.

Tags

CCSS.7.G.B.5

If it is a number, then it is either positive or negative. What is an appropriate counterexample?

• 10
• -2
• 0
• True. There is no counterexample.

Tags

CCSS.6.NS.C.6A

True or False: a counterexample is an example that makes a definition or conjecture incorrect

• True
• False

Which is a counterexample to the following statement?

If  $LM\cong MN$  , then  $M$   is the midpoint of  $LN$  .

• 
• 
• 
• None of these

Tags

CCSS.HSG.CO.B.6

CCSS.HSG.CO.C.10

Which is a counterexample to the following statement?

If two angles add up to  $180\degree$ , then they are a linear pair.

• 
• 
• 
• None of the above

Tags

CCSS.HSG.CO.C.9

Which is a counterexample to the following statement?

If you add two numbers, then the sum is odd.

• 2+5=7

• 3+2=5

• 1+8=9

• 2+4=6

Tags

CCSS.7.NS.A.1

CCSS.7.NS.A.3

Which is a counterexample to the following statement?

If a number is prime, then it is odd.

• 29

• 5

• 2

• 1

A counterexample is an example that proves a conjecture to be true.

• True

• False

To fully disprove a conjecture, one needs to find only ONE counterexample.

• True

• False