Identify the Graph for 3(2x-4y)=12 and (x+y)/3-y/3=7

System of Linear Equations with Mixed Forms

Which graph corresponds to the following equations?

3(2x4y)=12 3(2x-4y)=12

x+y3y3=7 \frac{x+y}{3}-\frac{y}{3}=7

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1

Understand the problem

Which graph corresponds to the following equations?

3(2x4y)=12 3(2x-4y)=12

x+y3y3=7 \frac{x+y}{3}-\frac{y}{3}=7

2

Step-by-step solution

To solve this problem, let's rewrite each equation in the slope-intercept form.

  • Equation 1: 3(2x4y)=12 3(2x - 4y) = 12

First, simplify this equation:

6x12y=12 6x - 12y = 12

Dividing the entire equation by 6 gives:

x2y=2 x - 2y = 2

Rearranging this equation to solve for y y :

2y=x+2 -2y = -x + 2

y=x21 y = \frac{x}{2} - 1

The slope of this line is 12 \frac{1}{2} , and the y-intercept is 1-1.

  • Equation 2: x+y3y3=7 \frac{x+y}{3} - \frac{y}{3} = 7

Simplify this equation:

x+y3y3=7\frac{x+y}{3} - \frac{y}{3} = 7

This simplifies to:

x3=7\frac{x}{3} = 7

Multiply through by 3 to solve for x x :

x=21 x = 21

Thus, x=21 x = 21 is a vertical line through x=21 x = 21 .

Now, comparing against the choices, while analyzing the slopes and intercepts:

The correct graph corresponds to lines: y=x21 y = \frac{x}{2} - 1 and x=21 x = 21 .

In the provided options, Choice 1 matches this description, as it contains a line with slope 12\frac{1}{2} and another vertical line.

Therefore, the graph corresponding to the given equations is Choice 1.

3

Final Answer

Key Points to Remember

Essential concepts to master this topic
  • Simplification: Convert both equations to standard or slope-intercept form first
  • Technique: First equation becomes y=x21 y = \frac{x}{2} - 1 , second becomes x=21 x = 21
  • Check: Verify slopes and intercepts match the graph visually ✓

Common Mistakes

Avoid these frequent errors
  • Not simplifying equations before graphing
    Don't try to graph 3(2x4y)=12 3(2x-4y)=12 directly = confusing slopes and intercepts! The distributive property and algebraic manipulation are hidden, making visualization impossible. Always simplify to y=mx+b y = mx + b or x=c x = c form first.

Practice Quiz

Test your knowledge with interactive questions

Which graph corresponds to the following equations?

\( 3(2x-4y)=12 \)\( \)

\( \frac{x+y}{3}-\frac{y}{3}=7 \)

FAQ

Everything you need to know about this question

How do I know which equation gives me a vertical line?

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When you simplify and get x equals a constant (like x=21 x = 21 ), that's always a vertical line! The y-value can be anything, but x stays the same.

Why does the second equation simplify to just x = 21?

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When you have x+y3y3=7 \frac{x+y}{3} - \frac{y}{3} = 7 , you can separate it: x3+y3y3=7 \frac{x}{3} + \frac{y}{3} - \frac{y}{3} = 7 . The y-terms cancel out completely, leaving just x3=7 \frac{x}{3} = 7 !

How can I tell which graph shows a slope of 1/2?

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A slope of 12 \frac{1}{2} means the line goes up 1 unit for every 2 units right. Look for a line that rises gently - not too steep, not horizontal.

What if I mess up the algebra when simplifying?

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Take your time with each step! Write out every step clearly: distribute first, then combine like terms, then isolate the variable. Check your work by substituting a point back into the original equation.

Do I need to find where these lines intersect?

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For this problem, you just need to identify the correct graph. But if you wanted the intersection, substitute x=21 x = 21 into y=x21 y = \frac{x}{2} - 1 to get the point (21, 9.5).

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