Question

n(n-3)/2=5 find n
Urgent.. Can you pls help me ​

Answer 1

$\frac{n(n-3)}{2} = 5$       => $n(n-3) = 5*2$     => $n^2 - 3n = 10$

=> $n^2 - 3n - 10 = 0$    => $n^2 +2n - 5n - 10 = 0$

=> $n(n+2) - 5 (n +2) = 0$   => $(n+2)(n-5) = 0$

n + 2 = 0         n - 5 = 0

n = -2              n = 5

the value of n is -2 or 5.

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