Proof by contrapositive Quiz
10 questions · easy to harder · Discrete Math · score and step-by-step answers
How it works
- 10 questions, about 30 minutes (a timer counts down; you can hide it). Solve it right here: no sign-up.
- 0 questions have choices. For the others you type the answer: a number like 4, −2, 7/2 or 3.5, or for example x = 4, x = 2 or x = −3, (3, 5), 2x + 1. Use ^ for powers (x^2) and sqrt for √. Any form with the same value counts (7/2 = 3.5).
- One question at a time: Back, Next, Mark for review and the question list at the bottom. A calculator is on the screen.
- At the end: your percent and grade, every question right or wrong, why a wrong choice is wrong, and its step-by-step solution. Then practise the lesson with new questions.
Your answers and results are kept in this browser only, so you can close the page and come back.
1 Question 1
Prove if n2 is even, then n is evenType the answer.
2 Question 2
Prove if 3n + 1 is even, then n is oddType the answer.
3 Question 3
Prove if n + 7 is odd, then n is evenType the answer.
4 Question 4
Prove if n2 + 4 is odd, then n is oddType the answer.
5 Question 5
Prove if xy is even, then x is even or y is evenType the answer.
6 Question 6
Prove if n2 + 2n is odd, then n is oddType the answer.
7 Question 7
Prove if n2 + 3 is even, then n is oddType the answer.
8 Question 8
Prove if x + y is odd, then x is odd or y is oddType the answer.
9 Question 9
Prove if n2 − 6n + 5 is even, then n is oddType the answer.
10 Question 10
Prove if n3 + 5 is odd, then n is evenType the answer.