It'd be easier to do #18 if y ou were to break it up:
14* (first term + 14th term)
Sum from n=1 to 14 of n = S = ---------------------------------
14 2
14(1+14)
= ---------------- = 7(15) = 105
2
The sum of twice that is 210. The sum of "1 from n=1 to n=14" is just 14.
The final sum is 210 + 14 = 224 (answer)
Answer:
n=-4 x=-7
Step-by-step explanation:
=-30
-2*-3=6
-1*5=-5
6 x -5=-30
Answer:
C
Step-by-step explanation:
Given
A = 
Substitute the given values with h = a, then
16.5 =
( multiply both sides by 2 )
33 = a(a + 8) ← distribute
33 = a² + 8a ( subtract 33 from both sides )
0 = a² + 8a - 33 ← in standard form
0 = (a + 11)(a - 3) ← in factored form
Equate each factor to zero and solve for a
a + 11 = 0 ⇒ a = - 11
a - 3 = 0 ⇒ a = 3
However, a > 0 thus a = 3
Hence the height is 3 feet