10.

A line passes through (–7, –5) and (–5, 4).Write an equation for the line in point-slope form.
Rewrite the equation in standard form using integers.

1 answer

To find the equation of the line in point-slope form, we first need to calculate the slope (\(m\)) of the line that passes through the points \((-7, -5)\) and \((-5, 4)\).

The formula for the slope \(m\) between two points \((x_1, y_1)\) and \((x_2, y_2)\) is given by:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Substituting the coordinates of the points:

\[ m = \frac{4 - (-5)}{-5 - (-7)} = \frac{4 + 5}{-5 + 7} = \frac{9}{2} \]

Now that we have the slope, we can use one of the points (let's use the point \((-7, -5)\)) to write the equation in point-slope form. The point-slope form is given by:

\[ y - y_1 = m(x - x_1) \]

Substituting the slope and the coordinates of the point:

\[ y - (-5) = \frac{9}{2}(x - (-7)) \]

Simplifying this, we have:

\[ y + 5 = \frac{9}{2}(x + 7) \]

This is the equation of the line in point-slope form.

Next, we will rewrite the equation in standard form. First, we will distribute and simplify the point-slope equation:

\[ y + 5 = \frac{9}{2}(x + 7) \]

Distributing \(\frac{9}{2}\) on the right:

\[ y + 5 = \frac{9}{2}x + \frac{63}{2} \]

Now, we will subtract \(5\) from both sides. Since \(5\) can be written as \(\frac{10}{2}\), we can write the equation as:

\[ y = \frac{9}{2}x + \frac{63}{2} - \frac{10}{2} \]

This simplifies to:

\[ y = \frac{9}{2}x + \frac{53}{2} \]

Next, to convert this to standard form \(Ax + By = C\) using integers, we can multiply through by \(2\) to eliminate the fractions:

\[ 2y = 9x + 53 \]

Rearranging it into standard form, we get:

\[ -9x + 2y = 53 \]

To follow the convention of \(A\) being positive, we can multiply the entire equation by \(-1\):

\[ 9x - 2y = -53 \]

Thus, the final standard form of the equation is:

\[ 9x - 2y = -53 \]

So the required equations are:

  • Point-slope form: \(y + 5 = \frac{9}{2}(x + 7)\)
  • Standard form: \(9x - 2y = -53\)