tmua 2017 Q5

tmua · Uk · paper2 1 marks Proof True/False Justification
Consider the following three statements:
$1 \quad 10 p ^ { 2 } + 1$ and $10 p ^ { 2 } - 1$ are both prime when $p$ is an odd prime.
2 Every prime greater than 5 is of the form $6 n + 1$ for some integer $n$.
3 No multiple of 7 greater than 7 is prime.
The result $91 = 7 \times 13$ can be used to provide a counterexample to which of the above statements?
A none of them
B 1 only
C 2 only
D 3 only
E 1 and 2 only
F 1 and 3 only
G 2 and 3 only
H 1, 2 and 3
& C
Consider the following three statements:

$1 \quad 10 p ^ { 2 } + 1$ and $10 p ^ { 2 } - 1$ are both prime when $p$ is an odd prime.

2 Every prime greater than 5 is of the form $6 n + 1$ for some integer $n$.

3 No multiple of 7 greater than 7 is prime.

The result $91 = 7 \times 13$ can be used to provide a counterexample to which of the above statements?

A none of them

B 1 only

C 2 only

D 3 only

E 1 and 2 only

F 1 and 3 only

G 2 and 3 only

H 1, 2 and 3