Because then you can just add the tops like they are
Answer:

Step-by-step explanation:
From the question we are told that
Charge 
Force 
Generally the equation for electric field strength is mathematically given as


Therefore

Answer:
center; single
Step-by-step explanation:
The measures of central tendency or center measures are a number that attempts to describe or summarize the entire data set by means of a single value that represents the center of its distribution. There are different measures of central tendency, and each of them is used depending on the characteristics of the data used.
Some examples of measure of central tendency are:
* Arithmetic mean
* Mode
* Median
* Geometric mean.
Therefore, based on what has been described above, the answer to this question is the third option: center; single
Then:
A measure of __center_____ summarizes all of the values in a data set with a ____single_______ number.
<u>Question 8</u>
a^2 + 7a + 12
= (a+3)(a+4)
When factorising a quadratic, the product of the two factors should equal the constant term (12), and the sum of the two factors should equal the linear term (7). To find the two factors, list out the factors of 12 (1x12, 2x6, 3x4) and identify the pair that adds up to 7 (3+4).
An alternative method if you get stuck during your exam would be to solve it algebraically using the quadratic formula and then write it in the factorised form.
a = (-7 +or- sqrt(7^2 - 4(1)(12)) / 2(1)
= (-7 +or- sqrt(1))/2
= -3 or -4
These factors are the negative of the values that would go in the brackets when written in factorised form, as when a = -3 the factor (a+3) would equal 0. (If it were positive 3 instead, then in the factorised form it would be a-3).
<u>Question 10</u>
-3(x - y)/9 + (4x - 7y)/2 - (x + y)/18
Rewrite each fraction with a common denominator so you can combine the fractions into one.
= -6(x - y)/18 + 9(4x - 7y)/18 - (x + y)/18
= (-6(x - y) + 9(4x - 7y) - (x + y)) /18
Expand the brackets and collect like terms.
= (-6x + 6y + 36x - 63y - x - y)/18
= (29x - 58y)/18
= 29/18 x - 29/9 y