Question

7pr=210 firn the value of r

Answer 1

7pr = 210
pr= 210/7
pr= 30
r=30/p

Answer 2

The value of r is 3

Step-by-step explanation:

Formula of permutation : $^nP_r=\frac{n!}{(n-r)!}$

We are given that $^7P_r=210$

Using formula :

$\frac{7!}{(7-r)!}=210$

$\frac{7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1}{(7-r)!}=210\\\frac{7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1}{210}=(7-r)!\\ 4 !=(7-r)!\\r=7-4\\r=3$

Hence the value of r is 3

#Learn more:

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