Answer:
-16
Step-by-step explanation:
X-6= -22
X = -22+6
X = - 16
The complete factorization of the equation 81x² - 100 is; (9x - 10)(9x + 10)
<h3>How to factorize quadratic equations?</h3>
We are given the quadratic equation;
81x² - 100
Now, according to quadratic identities, we know that;
(a + b) * (a - b) = a² - b²
Now, our equation can also be expressed as;
81x² - 100 = 9²x² - 10²
Thus, applying the quadratic identity gives us;
(9x + 10)(9x - 10)
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The probability expression is 
<h3>How to determine the probability expression?</h3>
The given parameters are
- Sophomore = 6
- Freshmen = 14
The total number of people is
n = 20
2 of the 20 people are to be selected.
So, the number of selection is

This gives

The expression that represents both students being sophomore is
--- i.e. 2 students selected from 6
The probability is then represented as:

Hence, the probability expression is 
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