Answer:
n(n+1)(n+5)/3
Step-by-step explanation:
there is no value, as we don't know n.
but we can create a summary formula/ function definition :
this is the sum for k = 1 to n of k×(k+3)
k×(k+3) = k² + 3k
so, the overall sum splits into the sum of k² for k=1 to n, and the sum of 3k for k=1 to n.
and the sum of 3k is 3 times the sum of k for k=1 to n.
Σk² for k=1 to n = [n(n+1)(2n+1)]/6
Σk for k=1 to n = n(n+1)/2
3×Σk for k=1 to n = 3×n(n+1)/2
so, we have a function formula
n(n+1)(2n+1)/6 + 3n(n+1)/2 = n(n+1)(2n+1)/6 + 9n(n+1)/6 =
= n(n+1)(2n+1+9)/6 = n(n+1)(2n+10)/6 = n(n+1)(n+5)/3
Answer:
-3x+12-9x+8=-3(4x-7)
-3x+12-9x+8=-12x+21
-12x+21=-12x+21
21=21
infinitely many solutions
hope this helps
have a good day :)
Step-by-step explanation:
Use Pythagorean thrm
17^2+10^2=21^2
289+100=441
389≠441
This is not a right triangle
First box is 6,464 feet. Second box is 4,061.5 feet.
