Question

if sigma n²=204 then n​

Answer 1

Answer:

n = 20

Step-by-step explanation:

\begin{gathered}\sum n = 210\\\\\text{And we know that }\sum n = \frac{n(n+1)}{2}\\\\\implies \frac{n(n+1)}{2}=210\\\\\implies n(n+1)=2\times 210\\\\\implies n^2+n-420=0\end{gathered}

∑n=210

And we know that ∑n=

2

n(n+1)

⟹

2

n(n+1)

=210

⟹n(n+1)=2×210

⟹n

2

+n−420=0

⇒ n² + 21n - 20n - 420 = 0

⇒ n(n + 21) - 20(n + 21) = 0

⇒ (n + 21)(n - 20) = 0

⇒ n = -21 or n = 20

Since, The number of terms cannot be a negative quantity so n = - 21 is rejected.

⇒ n = 20

Explanation:

hope it will help you

Answer 2

Answer:

the answer is n=20

Explanation:

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