suppose a square has a side length by the expression x+5/8x. what is the perimeter of the square?

This is equal to (x -5)(x - 5), or (x - 5)². 
Therefore, using the formula given above, the side's length is equal to (x - 5). 

Muliply that by four to obtain the perimeter. 

4(x - 5) = 4x -20. 

For the second problem, disregard the brackets since there are no other operations besides subtraction and addition. 

So it would become 3x^4 -x + 2 + 9x^5 - x² + x. 

Now simplify everything and rewrite it in decreasing terms of power, 

9x^5 + 3x^4 - x² + 2. 

(a) The probability of exactly 1 page has error is 0.271.

(b) The probability that there are at most 3 pages has error is 0.857.

Step-by-step explanation:

Let X = number of typos.

The probability of a typo is, P (X) = p = 0.005.

The number of pages in the novel is, n = 400.

The random variable X follows a Binomial distribution with parameter n and p.

But as the probability is very small and the sample size is too large we can use Poisson distribution to approximate the binomial distribution.

This distribution has parameter, .

The probability mass function of the Poisson distribution is:

(a)

Compute the probability of exactly 1 page has error as follows:

Thus, the probability of exactly 1 page has error is 0.271.

(b)

Compute the probability that there are at most 3 pages has error as follows:

P (X ≤ 3) = P (X = 0) + P (X = 1) + P (X = 2) + P (X = 3)

             

Thus, the probability that there are at most 3 pages has error is 0.857.