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:
2/6
Step-by-step explanation:
Ok, so if the fraction is 1/3 and the denominator needs to be 6, then what you do is figure out what would turn 3 into 6. So, 3 x 2 would equal 6 and then you would have to also keep that two and multiply that 2 with the 1 and you would get 2. That would lead to the numerator being 2 and the denominator being 6, or 2/6.
It's going to be number 4
Answer:
ST = 20
Step-by-step explanation:
Line segment RS and segment ST must add up to line segment RT
Step 1: Define
RS = 17
ST = x + 6
RT = 3x - 5
Step 2: Set up equation
mRS + mST = mRT
17 + x + 6 = 3x - 5
Step 3: Solve for <em>x</em>
x + 23 = 3x - 5
23 = 2x - 5
28 = 2x
x = 14
Step 3: Find mST
ST = x + 6
ST = 14 + 6
ST = 20