Find an equation of a line with a slope of -1 and having the point $(-2,-6)$ on the line. Then graph it.
To find the equation of a line, we identify its given properties: the slope \(m = -1\) and a point \(P = (-2, -6)\) through which it passes. The point-slope form of a linear equation is a powerful tool here:
\[y - y_1 = m(x - x_1)\]
where \((x_1, y_1)\) is the given point. Substituting the known values, we have:
\[y - (-6) = -1(x - (-2))\]
\[y + 6 = -1(x + 2)\]
To simplify the equation into the slope-intercept form, \(y = mx + b\), we solve for \(y\):
\[y + 6 = -x - 2\]
Subtracting \(6\) from both sides:
\[y = -x - 2 - 6\]
\[y = -x - 8\]
This is the equation of the line. The slope is \(-1\) and the y-intercept is \(-8\).
To visualize the line, we identify a few key points:
By plotting these points on a coordinate plane and drawing a straight line through them, we represent the linear relationship defined by \(y = -x - 8\).
This linear relationship can model real-world scenarios where something decreases at a constant rate. For example, if you have a balance of \$8 in a savings account and withdraw \$1 every day, your balance \(y\) after \(x\) days could be represented by the equation \(y = -1x + 8\). In our case, the negative slope indicates a steady decline over time. Understanding such relationships helps in budget planning, tracking consumption, or predicting how resources deplete over time.