Math Problem Statement

a) The coordinates (0, A) and (B, 0) lie on the line 3x - 4y = 12. What are the values of A and B? b) Use your answer to part a) to work out which line below is 3x - 4y = 12.

Solution

Let's solve the problem step by step:

Part (a) Find AA and BB:

The line equation is: 3x4y=123x - 4y = 12

  1. Find AA: When x=0x = 0, the point is (0,A)(0, A): 3(0)4A=12    4A=12    A=33(0) - 4A = 12 \implies -4A = 12 \implies A = -3 So the coordinate is (0,3)(0, -3).

  2. Find BB: When y=0y = 0, the point is (B,0)(B, 0): 3B4(0)=12    3B=12    B=43B - 4(0) = 12 \implies 3B = 12 \implies B = 4 So the coordinate is (4,0)(4, 0).

Thus, A=3A = -3 and B=4B = 4.


Part (b) Identify the line in the graph:

Using A=3A = -3 and B=4B = 4, the line passes through (0,3)(0, -3) and (4,0)(4, 0).

  • We can rewrite the equation into slope-intercept form y=mx+cy = mx + c: 3x4y=12    4y=3x+12    y=34x33x - 4y = 12 \implies -4y = -3x + 12 \implies y = \frac{3}{4}x - 3 The slope is 34\frac{3}{4}, and the y-intercept is 3-3.

  • Observing the graph:

    • The line with slope 34\frac{3}{4} and y-intercept 3-3 is labeled Line E.

Final Answer:

  1. A=3A = -3, B=4B = 4
  2. The line 3x4y=123x - 4y = 12 corresponds to Line E in the graph.

Would you like further clarification?

Here are 5 related questions for practice:

  1. Rewrite 3x4y=123x - 4y = 12 in standard, slope-intercept, and point-slope forms.
  2. Determine the slope of a line perpendicular to 3x4y=123x - 4y = 12.
  3. Find the equation of the line parallel to 3x4y=123x - 4y = 12 passing through (1,2)(1, 2).
  4. How do you find the x- and y-intercepts of any linear equation?
  5. Explain the steps to graph 3x4y=123x - 4y = 12 without a calculator.

Tip: Remember, you can always confirm intercepts by substituting x=0x = 0 or y=0y = 0 into the equation!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Intercepts
Graphing

Formulas

3x - 4y = 12
Slope-intercept form y = mx + c

Theorems

Linear relationship between x and y
Point-slope form derivation

Suitable Grade Level

Grades 8-10