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
The width of rectangular garden(b) = 8 feet and
The area of rectangular garden = 160 square feet
Step-by-step explanation:
Given,
The length of rectangular garden(l) = 20 feet and
The perimeter of rectangular garden(fencing) = 56 feet
To find, the width of rectangular garden(b) = ? and
The area of rectangular garden = ?
We know that,
The area of rectangular garden = 2(l + b)
⇒ 2(20 + b) = 56
⇒ 20 + b = 28
⇒ b = 28 - 20 = 8 feet
The width of rectangular garden(b) = 8 feet
∴ The area of rectangular garden = l × b
= 20 feet × 8 feet
= 160 square feet
Hence, the width of rectangular garden(b) = 8 feet and
the area of rectangular garden = 160 square feet
Area of trapezium = 1/2 (a + b) h = 1/2 (24 + 8) (6) = 96 cm²
Answer: 96 cm²
Answer:
18216
Step-by-step explanation:
