Answer:
10 terms
Step-by-step explanation:
equate the sum formula to 55 and solve for n
n(n + 1) = 55 ( multiply both sides by 2 to clear the fraction )
n(n + 1) = 110 ← distribute parenthesis on left side
n² + n = 110 ( subtract 110 from both sides )
n² + n - 110 = 0 ← in standard form
Consider the factors of the constant term (- 110) which sum to give the coefficient of the n- term (+ 1)
the factors are + 11 and - 10 , since
11 × - 10 = - 110 and 11 - 10 = + 1 , then
(n + 11)(n - 10) = 0 ← in factored form
equate each factor to zero and solve for n
n + 11 = 0 ⇒ n = - 11
n - 10 = 0 ⇒ n = 10
However, n > 0 , then n = 10
number of terms which sum to 55 is 10
1) given 6x = 4x + 140
2) subtract 4x from both sides => 6x - 4x = 4x - 4x + 140
=> 2x = 140
3) divide both members by 2 => 2x / 2 = 140 / 2
=> x = 70
4) Answer: x = 70
Let

. Then

, and differentiating both sides with respect to

gives


Now, when

, you get

You have

, so

and

. So
Answer:
By calculating the profit that will keep the business going
Y=2 7x2= 14
X= 7 4x7=28
28-14=14