y = x^2 + x + 11
The value of y is a prime number when x = 0,1,2 and 3.
The following statement is not true: "y = x^2 + x + 11 is always a prime number when x is an integer.
Show that the statement is not true.
2007-05-03 06:13:25 · 5 answers · asked by mbchelsea 1 in Science & Mathematics ➔ Mathematics
If x is a multiple of 11, then y will be a multiple of 11, so y will not be prime.
2007-05-03 08:07:37 · answer #1 · answered by mathematician 7 · 1⤊ 0⤋
This statement fails for x = 10 and x = 11.
For x = 10 you get 10²+10+11 = 121 = 11²
and for x = 11, you get 11²+11+11 = 11*13.
2007-05-03 14:01:39 · answer #2 · answered by steiner1745 7 · 0⤊ 1⤋
When x = 10, y = 121. 121 is not a prime number.
y = (10)^2 + (10) + 11
= (100) + (10) + 11
= 110 + 11
= 121
2007-05-03 13:29:31 · answer #3 · answered by John Z 1 · 0⤊ 1⤋
Counterexample:
x = 10
then y = 10*10 +10 +11
= 121,
which is NOT prime.
2007-05-03 13:22:24 · answer #4 · answered by Anonymous · 2⤊ 1⤋
for x=10 you get
y=10^2+10+11
y=121=11*11
2007-05-03 13:24:21 · answer #5 · answered by katsaounisvagelis 5 · 0⤊ 1⤋