Which is the better buy? $2.49 for 3 waters or $5.67 for 7 water’s
2 answers:
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The matrix represents the system:
-3x+5y=15
2x+3y=-10, which is choice c.
We can see it more clearly from the way we multiply matrices, as follows:
![\[ \left[ {\begin{array}{cc} -3 & 5 \\ \ 2 & 3 \\ \end{array} } \right] \] \cdot \[ \left[ {\begin{array}{c} x \\ y \\ \end{array} } \right] \]= \left[ {\begin{array}{c} -3\cdot x+5\cdot y \\ 2\cdot x+3\cdot y \\ \end{array} } \right] \]= \[ \left[ {\begin{array}{c} 15 \\ -10 \\ \end{array} } \right] \]](https://tex.z-dn.net/?f=%20%5C%5B%0A%20%20%5Cleft%5B%20%7B%5Cbegin%7Barray%7D%7Bcc%7D%0A%20%20%20-3%20%26%205%20%5C%5C%0A%20%20%20%20%5C%202%20%20%26%203%20%5C%5C%0A%20%20%5Cend%7Barray%7D%20%7D%20%5Cright%5D%0A%5C%5D%20%5Ccdot%20%20%5C%5B%0A%20%20%5Cleft%5B%20%7B%5Cbegin%7Barray%7D%7Bc%7D%0A%20%20%20x%20%5C%5C%0A%20%20%20%20y%20%5C%5C%0A%20%20%5Cend%7Barray%7D%20%7D%20%5Cright%5D%0A%5C%5D%3D%20%5Cleft%5B%20%7B%5Cbegin%7Barray%7D%7Bc%7D%0A%20%20%20-3%5Ccdot%20x%2B5%5Ccdot%20y%20%5C%5C%0A%20%20%20%202%5Ccdot%20x%2B3%5Ccdot%20y%20%5C%5C%0A%20%20%5Cend%7Barray%7D%20%7D%20%5Cright%5D%0A%5C%5D%3D%20%5C%5B%20%5Cleft%5B%20%7B%5Cbegin%7Barray%7D%7Bc%7D%2015%20%5C%5C%20-10%20%5C%5C%20%5Cend%7Barray%7D%20%7D%20%5Cright%5D%20%5C%5D)
Answer: C
-3x+5y=15
2x+3y=-10, which is choice c.
We can see it more clearly from the way we multiply matrices, as follows:
Answer: C
Answer (<u>assuming it can be in slope-intercept form)</u>:
y = -x - 1
Step-by-step explanation:
When knowing the slope of a line and its y-intercept, you can write an equation to represent it in slope-intercept form, or y = mx + b format. Substitute the m and b for real values.
1) First, find the slope of the equation, or m. Pick any two points from the line and substitute their x and y values into the slope formula, . I chose the points (0, -1) and (-1, 0):
Thus, the slope is -1.
2) Now, find the y-intercept, or b. The y-intercept of a line is the point at which the line crosses the y-axis. By reading the graph, we can see that the line intersects the y-axis at the point (0,-1), therefore that must be the y-intercept.
3) Now, substitute the found values into the y = mx + b formula. Substitute -1 for m and -1 for b: