Math Problem Statement

Write down the intersections with the x and y-axes respectively for each of the following lines: a) x + 2y =100 b) 4x +5y = -30 c) 10x -5y = 20 d) x = y +15

Solution

To find the intersections with the x-axis and y-axis for each of the given lines, we follow these steps:

  • For the x-axis intersection, set y=0y = 0 and solve for xx.
  • For the y-axis intersection, set x=0x = 0 and solve for yy.

a) x+2y=100x + 2y = 100

  1. X-axis intersection (Set y=0y = 0): x+2(0)=100    x=100x + 2(0) = 100 \implies x = 100 Intersection with the x-axis: (100,0)(100, 0).

  2. Y-axis intersection (Set x=0x = 0): 0+2y=100    y=1002=500 + 2y = 100 \implies y = \frac{100}{2} = 50 Intersection with the y-axis: (0,50)(0, 50).


b) 4x+5y=304x + 5y = -30

  1. X-axis intersection (Set y=0y = 0): 4x+5(0)=30    4x=30    x=304=7.54x + 5(0) = -30 \implies 4x = -30 \implies x = \frac{-30}{4} = -7.5 Intersection with the x-axis: (7.5,0)(-7.5, 0).

  2. Y-axis intersection (Set x=0x = 0): 4(0)+5y=30    5y=30    y=305=64(0) + 5y = -30 \implies 5y = -30 \implies y = \frac{-30}{5} = -6 Intersection with the y-axis: (0,6)(0, -6).


c) 10x5y=2010x - 5y = 20

  1. X-axis intersection (Set y=0y = 0): 10x5(0)=20    10x=20    x=2010=210x - 5(0) = 20 \implies 10x = 20 \implies x = \frac{20}{10} = 2 Intersection with the x-axis: (2,0)(2, 0).

  2. Y-axis intersection (Set x=0x = 0): 10(0)5y=20    5y=20    y=205=410(0) - 5y = 20 \implies -5y = 20 \implies y = \frac{-20}{5} = -4 Intersection with the y-axis: (0,4)(0, -4).


d) x=y+15x = y + 15

  1. X-axis intersection (Set y=0y = 0): x=0+15    x=15x = 0 + 15 \implies x = 15 Intersection with the x-axis: (15,0)(15, 0).

  2. Y-axis intersection (Set x=0x = 0): 0=y+15    y=150 = y + 15 \implies y = -15 Intersection with the y-axis: (0,15)(0, -15).


Final answers:

  • a) X-axis: (100,0)(100, 0), Y-axis: (0,50)(0, 50)
  • b) X-axis: (7.5,0)(-7.5, 0), Y-axis: (0,6)(0, -6)
  • c) X-axis: (2,0)(2, 0), Y-axis: (0,4)(0, -4)
  • d) X-axis: (15,0)(15, 0), Y-axis: (0,15)(0, -15)

Let me know if you'd like more details or have any questions!
Here are 5 follow-up questions:

  1. How would you find the slope of the line x+2y=100x + 2y = 100?
  2. What does the intersection point represent geometrically?
  3. How would you find the intersection of two lines, for example 4x+5y=304x + 5y = -30 and 10x5y=2010x - 5y = 20?
  4. How does the equation x=y+15x = y + 15 differ from the others in terms of graphing?
  5. What would be the general form of a line equation?

Tip: The x-intercept is found by setting y=0y = 0 because any point on the x-axis has a yy-coordinate of zero.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Coordinate Geometry

Formulas

x-intercept: Set y = 0 and solve for x
y-intercept: Set x = 0 and solve for y

Theorems

Intercept Theorem

Suitable Grade Level

Grades 8-10