Answer:
257 is prime.
Step-by-step explanation:
To evaluate if a number is prime, we just need to evaluate it for the prime numbers that are equal or lesser than the said number's square root.
In this case, √257 = 16.03 so we just need to see if 257 is divisible by <u>2, 3, 5, 7, 11 and 13</u> (the prime numbers that come before 16)
- 257 is odd, so it is not divisible by 2.
- The sum of its digits is 14, therefore, it is not divisible by 3.
- 257 ends in 7, therefore it's not divisible by 5.
- 257/ 7 = 36.71 so it's not divisible by 7.
- 257/ 11 = 23.36 so it's not divisible by 11
- Finally 257 / 13= 19.76 so it's not divisible by 13.
Therefore, 257 is prime.
Answer:
The correct answer is marked.
Step-by-step explanation:
The solution is easily found using synthetic division. The attachment shows how that is done, and what the result is.
0.600. If I'm wrong please tell me so I can correct my answer and recalculate it.
Step-by-step explanation:
4x2 - 25b2
We can solve it by the squares so
(2x - 5b) (2x + 5b)
2) x2 - 81
The same case is here so
(x - 9) (x + 9)