Math Problem Statement

Find a linear equation whose graph is the straight line with the given properties: through (1/8, -1) and parallel to the line 8x - 9y = 8.

Solution

We are tasked with finding a linear equation of a line that passes through the point (18,1)\left(\frac{1}{8}, -1\right) and is parallel to the line 8x9y=88x - 9y = 8.

Step 1: Identify the slope of the given line.

The given line is 8x9y=88x - 9y = 8. To find its slope, we need to rewrite the equation in slope-intercept form y=mx+by = mx + b, where mm is the slope.

Start by solving for yy:

8x9y=88x - 9y = 8 9y=8x+8-9y = -8x + 8 y=89x89y = \frac{8}{9}x - \frac{8}{9}

Thus, the slope of the given line is m=89m = \frac{8}{9}.

Step 2: Use the point-slope form.

Since the new line is parallel to the given line, it will have the same slope. The equation of a line with slope mm passing through a point (x1,y1)(x_1, y_1) is given by the point-slope form:

yy1=m(xx1)y - y_1 = m(x - x_1)

Here, the point is (18,1)\left(\frac{1}{8}, -1\right) and the slope is m=89m = \frac{8}{9}. Substituting these values into the equation:

y(1)=89(x18)y - (-1) = \frac{8}{9}\left(x - \frac{1}{8}\right) y+1=89x89×18y + 1 = \frac{8}{9}x - \frac{8}{9} \times \frac{1}{8} y+1=89x19y + 1 = \frac{8}{9}x - \frac{1}{9}

Step 3: Simplify the equation.

Now, subtract 1 from both sides to get the final equation:

y=89x191y = \frac{8}{9}x - \frac{1}{9} - 1 y=89x1999y = \frac{8}{9}x - \frac{1}{9} - \frac{9}{9} y=89x109y = \frac{8}{9}x - \frac{10}{9}

Thus, the equation of the line is:

y(x)=89x109y(x) = \frac{8}{9}x - \frac{10}{9}

Let me know if you'd like further explanation or have any questions! Here are a few related questions:

  1. How do you find the slope of a line from its general form?
  2. What is the significance of parallel lines in terms of slope?
  3. How would you find the equation of a line perpendicular to 8x9y=88x - 9y = 8?
  4. Can you explain the steps involved in converting from standard form to slope-intercept form?
  5. How would the equation change if the line passed through a different point but remained parallel?

Tip: Always check if the given line is in standard form; rewriting it in slope-intercept form will help you easily identify its slope.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Parallel Lines
Slope-Intercept Form
Point-Slope Form

Formulas

y = mx + b
y - y1 = m(x - x1)

Theorems

Slope of parallel lines

Suitable Grade Level

Grades 8-10