i am a 2 dimensional shape that has four sides. I have four 90 degree angles.i have two sets of parallel lines. i also have two
2 answers:
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Answer:
C. 1 / (a(a - 1))
Step-by-step explanation:
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Just know that:
n! = n(n-1)!
= n(n-1)(n-2)!
= n(n-1)(n-2)(n-3)!
= ...
