Parallelogram WXYZ has vertices W(0, 0) , X(1, 2) , Y(4, 2) , and Z(3, 0) . The parallelogram is dilated, and the vertices of th
e image are W'(0, 0) , X'(2, 4) , Y'(8, 4) , and Z'(6, 0) . The center of dilation is the origin. What is the scale factor of the dilation? Enter your answer in the box. Parallelogram WXYZ was dilated by a scale factor of .
The system of equations is x + y = 85 and 7/20x+2/5y=31
To eliminate the x-variable from the equations, you can multiply the equation with the fractions by 20 and multiply the other equation by -7.
B-She used 60 minutes for calling and 25 minutes for data.
Step-by-step explanation:
It is always a good idea to start by defining variables in such a problem. Here, we can let x represent the number of calling minutes, and y represent the number of data minutes. The the total number of minutes used is ...
x + y = 85
The total of charges is the sum of the products of charge per minute and minutes used:
7/20x + 2/5y = 31.00
We can eliminate the x-variable in these equations by multiplying the first by -7 and the second by 20, then adding the result.
Remember, if you multiply a negative number by a negative number, you will get a positive number, and positive numbers are greater than negative numbers. In this case, if I were to multiply each of these expressions with -1, I would get the following:
7(-1)+4=-3
-1-4=-5
5(-1)=-5
-5(-1)=5
And I'm sure you can imply how these values will correspond to other negative values. Basically, the last expression gives us a positive answer, which is larger than the others (which give a negative answer).
In order to find any of the info we need we have to find the first derivative of the equation. If , then . We are told to find the slope at point (1, 7). Using that x value in our derivative will give us the slope of the line at that point. y' = -(1)^2+8. So y' = 7. That's the slope of the line. Now we will use that slope along with the x and y coordinate in the slope-intercept form of a line to solve for b. 7 = 7(1) + b so b = 0. Our equation then is y = 7x. If you graph these in the same window on your calculator, you can see how perfectly that align at the given point. It's really quite perfect.