keeping in mind that perpendicular lines have <u>negative reciprocal</u> slopes, let's find the slope of 3x + 4y = 9, by simply putting it in slope-intercept form.
![\bf 3x+4y=9\implies 4y=-3x+9\implies y=-\cfrac{3x+9}{4}\implies y=\stackrel{slope}{-\cfrac{3}{4}}x+\cfrac{9}{4} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \stackrel{\textit{perpendicular lines have \underline{negative reciprocal} slopes}} {\stackrel{slope}{-\cfrac{3}{4}}\qquad \qquad \qquad \stackrel{reciprocal}{-\cfrac{4}{3}}\qquad \stackrel{negative~reciprocal}{+\cfrac{4}{3}}\implies \cfrac{4}{3}}](https://tex.z-dn.net/?f=%20%5Cbf%203x%2B4y%3D9%5Cimplies%204y%3D-3x%2B9%5Cimplies%20y%3D-%5Ccfrac%7B3x%2B9%7D%7B4%7D%5Cimplies%20y%3D%5Cstackrel%7Bslope%7D%7B-%5Ccfrac%7B3%7D%7B4%7D%7Dx%2B%5Ccfrac%7B9%7D%7B4%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20%5Cstackrel%7B%5Ctextit%7Bperpendicular%20lines%20have%20%5Cunderline%7Bnegative%20reciprocal%7D%20slopes%7D%7D%20%7B%5Cstackrel%7Bslope%7D%7B-%5Ccfrac%7B3%7D%7B4%7D%7D%5Cqquad%20%5Cqquad%20%5Cqquad%20%5Cstackrel%7Breciprocal%7D%7B-%5Ccfrac%7B4%7D%7B3%7D%7D%5Cqquad%20%5Cstackrel%7Bnegative~reciprocal%7D%7B%2B%5Ccfrac%7B4%7D%7B3%7D%7D%5Cimplies%20%5Ccfrac%7B4%7D%7B3%7D%7D%20)
so we're really looking for the equation of a line whose slope is 4/3 and runs through 8, -4.

there are 36 inches in a yard
Let x be the number of times they raise the price on the newspaper. Then the new cost of the newspaper is

Let y be the newspaper they sell, then the income will be

Now, we know that the circulation is of 500, assuming that they sold every newspaper at the original price now the number the will sell will be

Plugging the value of y in the first expression we have that the income will be

Then the income is given by the function

To find the maximum value of this functions (thus the maximum income) we need to take the derivative of the function,

no we equate the derivative to zero and solve for x.

This means that we have an extreme value of the function when x=9. Now we need to find out if this value is a maximum or a minimum. To do this we need to take the second derivative of the function, then

Since the second derivative is negative in the point x=9, we conclude that this value is a maximum of the function.
With this we conclude that the number of times that they should raise the price to maximize the income is 9. This means that they will raise the price of the newspaper (9)($0.05)=$0.45.
Therefore the price to maximize the income is $0.35+$0.45=$0.80.
<u>ANSWER</u>
1. 
2. 
<u>QUESTION 1</u>
The first sentence is
.
Recall that;

We simplify the left hand side by applying this property to get;
.
.
We now rewrite the right hand side too in an index form to obtain;

We now equate the exponents to get;
.

.
<u>QUESTION 2</u>
The second sentence is 
We simplify the left hand side first to get;


We now rewrite the left hand side too in index form to obtain;

We equate the exponents to get;

This implies that;

or
