Math Problem Statement

Write an equation of each line in standard form with integer coefficients for the following problems: 11. the line through (2, 3) and (4, 5) 12. the line through (-4, 6) and (2, -2) 13. the line through (-4, 2) with slope 3 14. the line through (1, 2) with slope 4/5 15. a line through (3, 1) with slope 0 16. a line with slope 2/3 and y-intercept (0, 5) 17. 2y = -4x - 12 18. 2/3x + 3 = 6y - 15

Solution

Let's work through each of the problems one by one, converting the given line information into standard form with integer coefficients.

Problem 11: The line through (2, 3) and (4, 5)

  1. First, calculate the slope (m)(m) using the formula: m=y2y1x2x1=5342=1m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{5 - 3}{4 - 2} = 1
  2. Now use the point-slope form: yy1=m(xx1)y - y_1 = m(x - x_1). Pick the point (2,3)(2, 3): y3=1(x2)y=x+1y - 3 = 1(x - 2) \quad \Rightarrow \quad y = x + 1
  3. Convert to standard form: Ax+By=CAx + By = C: xy=1(which is already in integer form!)x - y = -1 \quad (\text{which is already in integer form!})

Problem 12: The line through (4,6)(-4, 6) and (2,2)(2, -2)

  1. Calculate the slope: m=262(4)=86=43m = \frac{-2 - 6}{2 - (-4)} = \frac{-8}{6} = -\frac{4}{3}
  2. Use the point-slope form with point (4,6)(-4, 6): y6=43(x+4)y - 6 = -\frac{4}{3}(x + 4) Simplify: y6=43x163y=43x+23y - 6 = -\frac{4}{3}x - \frac{16}{3} \quad \Rightarrow \quad y = -\frac{4}{3}x + \frac{2}{3}
  3. Multiply everything by 3 to eliminate fractions: 3y=4x+24x+3y=23y = -4x + 2 \quad \Rightarrow \quad 4x + 3y = 2

Problem 13: The line through (4,2)(-4, 2) with slope 3

  1. Start with the point-slope form using point (4,2)(-4, 2): y2=3(x+4)y - 2 = 3(x + 4) Simplify: y2=3x+12y=3x+14y - 2 = 3x + 12 \quad \Rightarrow \quad y = 3x + 14
  2. Convert to standard form: 3xy=143x - y = -14

Problem 14: The line through (1,2)(1, 2) with slope 45\frac{4}{5}

  1. Start with the point-slope form using point (1,2)(1, 2): y2=45(x1)y - 2 = \frac{4}{5}(x - 1) Simplify: y2=45x45y=45x+65y - 2 = \frac{4}{5}x - \frac{4}{5} \quad \Rightarrow \quad y = \frac{4}{5}x + \frac{6}{5}
  2. Multiply everything by 5 to eliminate fractions: 5y=4x+64x5y=65y = 4x + 6 \quad \Rightarrow \quad 4x - 5y = -6

Problem 15: A line through (3,1)(3, 1) with slope 0

  1. Since the slope is 0, the line is horizontal, and the equation is simply y=1y = 1.
  2. In standard form, this is: 0x+y=10x + y = 1

Problem 16: A line with slope 23\frac{2}{3} and y-intercept (0,5)(0, 5)

  1. The slope-intercept form is: y=23x+5y = \frac{2}{3}x + 5
  2. Multiply everything by 3: 3y=2x+152x3y=153y = 2x + 15 \quad \Rightarrow \quad 2x - 3y = -15

Problem 17: 2y=4x122y = -4x - 12

  1. Divide by 2: y=2x6y = -2x - 6
  2. Rearrange into standard form: 2x+y=62x + y = -6

Problem 18: 23x+3=6y15\frac{2}{3}x + 3 = 6y - 15

  1. First, eliminate the fraction by multiplying through by 3: 2x+9=18y452x + 9 = 18y - 45
  2. Simplify and rearrange: 2x18y=542x - 18y = -54 Divide through by 2 to get the simplest integer coefficients: x9y=27x - 9y = -27

Would you like further details on any of these problems? Here are five related questions to expand your understanding:

  1. How do you find the equation of a line parallel to a given line?
  2. What is the relationship between slopes of perpendicular lines?
  3. How can you verify that two points lie on a given line equation?
  4. How can you convert a line equation from slope-intercept form to point-slope form?
  5. What is the significance of the standard form of a line equation?

Tip: Always check your final equation by plugging in one of the original points to ensure the equation is correct!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Point-Slope Form
Standard Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Point-slope form: y - y1 = m(x - x1)
Standard form: Ax + By = C

Theorems

Slope-intercept form of a line
Conversion between point-slope and standard forms

Suitable Grade Level

Grades 8-10