Answer:
The product of (k + 1) series starts with 3 (because k = 2) and you need 2 to be multiplied to this in order to get (n + 1)!
Therefore you need to multiply 2 and 1/2 to make it right. 2 completes the factorial and 1/2 remains.
Hope it was clear explanation.
The 2 smallest lengths in a triangle have to add up to be greater that the longest side of the triangle. In this case, the longest side is 20. The 2 smallest sides are 5 and 10. 5+10=15, but 15<20. This is why these 3 lengths can’t create a triangle.
The square root of 81 is 9
simplified it would be - 
</h2><h2>Hope this helps!!</h2>
