Question

If nP7=42^np5,then n=?.Please answer ASAP

Answer 1

Answer:

n(n-1)(n-2)(n-3)(n-4)(n-5)(n-6)=42.n(n-1)(n-2)(n-3)(n-4)

(n-5)(n-6)=42

(n-5)(n-6)=7×6

(n-5)=7

n -5 = 7

n = 7+5

n = 12

this is your answer..

Answer 2

np7=42.np5

n * (n-1) * (n-2) * (n-3) * (n-4) * (n-5) * (n-6) = 42 * n * (n-1) * (n-2) * (n-3) * (n-4)

=> (n - 5) * (n - 6) = 42

=> n² - 6n - 5n + 30 = 42

=> n² - 11n - 12 = 0

=> n² + n - 12n - 12 = 0

=> n(n + 1) - 12(n + 1) = 0

=> n = 12, -1[avoid negative values]

=> n = 12

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