Step-by-step explanation:
We have,,
6x and 2x
To find, the value of x = ?
According to question,
The sum of 6x and 2x is at least 39
∴ 6x + 2x = 39
⇒ 8x = 39
⇒ x =
∴ The value of x =
Thus, put x = I write the sum of 6x and 2x is at least 39 .
The average rate of change is also known as the slope. If we are looking to find the average rate of change between x = -1 and x = 2, in order to find the slope between those 2 x values, we need the y's that go along with them. Fill in -1 for x in the function and solve for y: . That means that the coordinate is (-1, 0). Fill in 2 for x in the function and solve for y:
. The coordinate there is (2, -3). Now we can set up the slope formula to find the average rate of change between those 2 points:
. Therefore, the average rate of change between x = -1 and x = 2 is -1
Answer:
-10
Step-by-step explanation:
You are asked to tell the y-value of the solution. You can find the whole solution and then report the y-value, or you can just find the y part of the solution. We choose the latter.
This is basically done by eliminating the x-variable. It can be done using the "elimination" method of solving these equations. And it can also be done using the "substitution" method of solving these equations. We choose the latter.
Add 14 to the second equation to solve for x:
... x = y + 14
Substitute this into the first equation.
... 3(y +14) -y = 22
... 2y +42 = 22 . . . . . . simplify
... y +21 = 11 . . . . . . . . divide by 2
... y = -10 . . . . . . . . . . subtract 21
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<em>Comment on additional solution methods</em>
A graphing calculator can show you the solution, as in the attachment. Of the solution (x, y) = (4, -10), we are only interested in y = -10.
Cramer's rule can find just one variable value, too. For that, it is convenient to write the system as ...
Then the solution for y is ...
... y = (22·1 -14·3)/(-1·1 -(-1)·3) = -20/2 = -10
