Answer:
see explanation
Step-by-step explanation:
the sum to n terms of an arithmetic sequence is
= 
[2a + (n - 1)d ]
where d is the common difference and a is the first term
here d = 9 - 7 = 7 - 5 = 2 and a = 5, hence
= [(2 × 5) + 2(n - 1) ]
= (10 + 2n - 2)
= (2n + 8)
= n² + 4n
When sum = 165, then
n² + 4n = 165 ← rearrange into standard form
n² + 4n - 165 = 0 ← in standard form
(n + 15)(n - 11) = 0 ← in factored form
equate each factor to zero and solve for n
n + 15 = 0 ⇒ n = - 15
n - 11 = 0 ⇒ n = 11
but n > 0 ⇒ n = 11
Answer:
Below.
Step-by-step explanation:
15y + 12x = 18
5y + 4x = 6
The second equations is the first times 3 so they are basically the same.
Infinite Solutions.
2x+ 3y= 12
-6y= 4x-24 Rearranging the second equation:
-4x - 6y = -24 Multiplying the first equation by 2:
4x + 6y = 24
- we see that the last equation is -1 * previous equation.
So there are infinite solutions.
Use the Pythagorean Theorem:
a^2 + b^2= c^2
a= one side= 68 mi
b= second side= 80 mi
c= hypotenuse= Greenville to Columbia mi
a^2 + b^2= c^2
68^2 + 80^2= c^2
square each number
4,624 + 6,400= c^2
11,024= c^2
take square root of both sides
104.995 mi= c
ANSWER: The distance from Greenville to Columbia is 104.995 miles (rounded to 105 miles).
Hope this helps! :)
Answer:
30, 30, 120
Step-by-step explanation:
Answer: 410 square km
Step-by-step explanation:
The area of each of the triangles with their base on the 10 km side is 
, so their combined area is 
.
The area of each of the triangles with their base on the 12 km side is 
, so their combined area is 
.
The area of the bottom rectangular face is 
.
So, the total surface area is 
