(x 4 - 81) (x - 3) . write answers in descending power of x. (division)

  x^3+3x^2+9x+27

Step-by-step explanation:

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The factoring of the difference of squares is used (twice):

  a² -b² = (a -b)(a +b)

29.  A) mean:  87.2; median:  85.5; mode:  83

30.  D) 5.1

Step-by-step explanation:

29.  To find the mean of a data set, add together all of the numbers:

83+85+82+93+83+84+95+87+86+94 = 872

Now divide by the number of data points:

872/10 = 87.2.

The median is found by first putting the numbers in order from least to greatest:

82, 83, 83, 84, 85, 86, 87, 93, 94, 95

Now we look for the middle number.  Since we have an even number of data values, the median is between 85 and 86:

(85+86)/2 = 171/2 = 85.5

The mode is the data value that occurs most often.  In this set, that is 83.

30.  To find the standard deviation of a data set, we first find the mean:

(81+84+82+93+81+85+95+89+86+94) = 870/10 = 87

Find the difference between each data point and the mean; square each difference; find the sum of these; divide by the number of data points; and take the square root: