First slide

Permutations

Question

If $m + n_{P_{2}} = 90$ and $^{m - n} P_{2} = 30,$ then $(m, n)$ is equal to

Moderate

A

(12, 8)
B

(8, 2)
C

(6, 4)
D

(7, 4)

Solution

$(m + n) (m + n - 1) = 90$ and
$\begin{array}{l} (m - n) (m - n - 1) = 30 \\ \Rightarrow m + n = 10, m - n = 6 \\ ∴ m = 8, n = 2 \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App