Question

Write the equation of each line in general form. Slope \(=-2 ;\) passes through (-2,-3)

Short answer

The equation of the line in general form is \(2x + y = -7\).

Step-by-step solution

Use Point-Slope Form

Since we know the slope \textbf{m} of the line and a point \textbf{(x1, y1)} = (-2, -3) through which the line passes, we can use the point-slope form of a line equation: \[y - y_1 = m(x - x_1)\].

Plug in the slope and point coordinates

Substitute the slope \textbf{m} = -2 and the coordinates of the point \textbf{(-2, -3)} into the equation: \[y - (-3) = -2(x - (-2))\].

Simplify the Equation

Simplify the equation by performing the operations:\[y + 3 = -2(x + 2)\].Next, distribute the -2:\[y + 3 = -2x - 4\].

Write in General Form

To write the equation in general form \textbf{Ax + By = C}, we need to rearrange the terms so that all variables and constants are on one side of the equation: \[2x + y = -3 - 4\].Combining like terms gives us the final equation in general form: \[2x + y = -7\].

Key concepts

Point-Slope Form

When we know a point on a line and its slope, the point-slope form is an efficient way to write the equation of a line. It's given as \[y - y_1 = m(x - x_1)\] where \(m\) is the slope of the line and \(x_1, y_1\) are the coordinates of the known point. The beauty of this form is in its directness; with the slope and a single point, we can immediately start crafting the line's equation.

For instance, given a slope of -2 and a point at (-2, -3), the point-slope form allows us to create the foundational equation \[y - (-3) = -2(x - (-2))\]. Notice how we substitute our known values directly into the equation. Despite its simplicity, the point-slope form isn't the final form we usually need, which is where simplification comes into play.

Simplify Linear Equations

The process of simplifying linear equations transforms them into a more usable form, often making them easier to interpret or solve. Simplification might involve distributing multiplication, combining like terms, and moving terms from one side of the equation to the other to isolate variables.

Using the point-slope equation from our previous example, we distribute the slope -2 across the parentheses resulting in \[y + 3 = -2x -4\]. Here, the equation is simplified, but it's still not in the standard 'general form' that many prefer for linear equations. We continue by moving the variables and constants around, keeping the equation balanced, until we achieve the desired format.

Linear Equations

Linear equations form the bedrock of algebra and are the basis for graphing lines on the coordinate plane. They describe a relationship between two variables, typically \(x\) and \(y\), such that the plot of their interactions will always be a straight line.

General form of a linear equation is often represented as \[Ax + By = C\], where \(A\), \(B\), and \(C\) are real numbers and \(A\) and \(B\) are not both zero. This form is vastly used because it neatly presents the equation without fractions and makes the x and y-intercepts more apparent. In our example, the simplified equation \[2x + y = -7\] neatly fits this description. It's easy to graph: its standardized appearance allows us to swiftly identify the slope and intercepts, rendering it a powerful tool for mathematicians.