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:
x = 3
Step-by-step explanation:
2x+6=x+9 subtract x in both sides
x +6 =9 subtract 6 in both sides
x = 3
Answer:
first, subtract 17 on both sides: x²+2x-16=0
this cannot be factored, so use the quadratic formula to solve for x:
b²-4ac=2²-4(10(-16)=4+64=68
√68=2√17
so x=(-2+2√17)/2 or x=(-2-2√17)/2
x=-1+√17 or x=-1-√17
Step-by-step explanation:
Answer:
B
x is the price of the sweater so 3x and add $15 for the skirt which would add up to $90
Answer:
I think it is F
Step-by-step explanation:
