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
I think that 0.45 would be one.
Answer:
x² - 7x - 18
Step-by-step explanation:
Remember to follow FOIL.
First, multiply the first. (x)(x) = x²
Next, multiply the second. (x)(2) = 2x
Then, multiply the third. (-9)(x) = -9x
Finally, multiply the last. (-9)(2) = -18
Combine like terms: x² + 2x - 9x - 18
x² - 7x - 18
x² - 7x - 18 is your answer.
~
Answer: 621
Step-by-step explanation: 28^2+ 13 − 176
length, width, and height.