Answer:
Let x and y be the two positive integers the Christopher is thinking.
x is equal to 7
and y =20
I'm going to use the substitution method.
4x + 4y = -16
-8x - 6y = -20
4x + 4y = -16
- 4x - 4x
--------------------------
4y = -4x - 16
------ ------ ------
4 4 4
y = -x - 4
-8x - 6(-x - 4) = -20
-8x + 6x + 24 = -20
-2x + 24 = -20
- 24 - 24
----------------------------
-2x = 44
------- -------
2 2
x = 22
4(22) + 4y = -16
88 + 4y = -16
- 88 - 88
------------------------
4y = -104
------ ---------
4 4
y = -26
The answer is (22, -26).
The 90% confidence interval is (70 - 4, 70 + 4). The margin of error is 4%.
If there is 20 pencils there will be 5 erasers 20:5
Answer:
- The sequence of transformations that maps triangle XYZ onto triangle X"Y"Z" is <u>translation 5 units to the left, followed by translation 1 unit down, and relfection accross the x-axis</u>.
Explanation:
By inspection (watching the figure), you can tell that to transform the triangle XY onto triangle X"Y"Z", you must slide the former 5 units to the left, 1 unit down, and, finally, reflect it across the x-axys.
You can check that analitically
Departing from the triangle: XYZ
- <u>Translation 5 units to the left</u>: (x,y) → (x - 5, y)
- Vertex X: (-6,2) → (-6 - 5, 2) = (-11,2)
- Vertex Y: (-4, 7) → (-4 - 5, 7) = (-9,7)
- Vertex Z: (-2, 2) → (-2 -5, 2) = (-7, 2)
- <u>Translation 1 unit down</u>: (x,y) → (x, y-1)
- (-11,2) → (-11, 2 - 1) = (-11, 1)
- (-9,7) → (-9, 7 - 1) = (-9, 6)
- (-7, 2) → (-7, 2 - 1) = (-7, 1)
- <u>Reflextion accross the x-axis</u>: (x,y) → (x, -y)
- (-11, 1) → (-11, -1), which are the coordinates of vertex X"
- (-9, 6) → (-9, -6), which are the coordinates of vertex Y""
- (-7, 1) → (-7, -1), which are the coordinates of vertex Z"
Thus, in conclusion, it is proved that the sequence of transformations that maps triangle XYZ onto triangle X"Y"Z" is translation 5 units to the left, followed by translation 1 unit down, and relfection accross the x-axis.
