Identify Linear Functions Among Given Equations: Which Are Parallel?

Linear Functions with Parallel Line Identification

Which of the following represent linear functions and parallel lines?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Choose the functions that are linear and parallel
00:03 Linear function with slope of one-half
00:07 Open parentheses properly, multiply by each factor
00:11 Linear function with slope of one-half
00:17 Functions are parallel when their slopes are equal, therefore they match
00:22 Open parentheses properly, multiply by each factor
00:25 Linear function with slope of 3
00:28 This function is not linear because X is squared
00:41 Linear function with slope of 12
00:47 Linear function with slope of 1
00:52 Functions are parallel when their slopes are equal, therefore they don't match
00:55 Linear function with slope of 3
00:58 Linear function with slope of 2
01:01 Functions are parallel when their slopes are equal, therefore they don't match
01:03 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Which of the following represent linear functions and parallel lines?

2

Step-by-step solution

To solve this problem, we'll analyze each pair of given equations to see if they are linear and parallel.

Let's examine each pair:

  • Choice 1:
    y=12x+10 y = \frac{1}{2}x + 10
    y=12(x+2) y = \frac{1}{2}(x + 2) simplifies to y=12x+1 y = \frac{1}{2}x + 1
    Both equations are linear with the same slope of 12 \frac{1}{2} , indicating they are parallel.
  • Choice 2:
    y=3(x+4) y = 3(x + 4) simplifies to y=3x+12 y = 3x + 12
    y=3x2+12 y = 3x^2 + 12 is not in the form y=mx+b y = mx + b as it includes an x2 x^2 term. Thus, it is non-linear.
  • Choice 3:
    y=5+12x y = 5 + 12x is already in the form y=mx+b y = mx + b with m=12 m = 12
    y=5+12+x y = 5 + 12 + x simplifies to y=x+17 y = x + 17 , which has a slope of 1.
    Slopes are different, so not parallel.
  • Choice 4:
    y=3x+2 y = 3x + 2 , slope m=3 m = 3
    y=2x+3 y = 2x + 3 , slope m=2 m = 2
    Different slopes, thus not parallel.

Therefore, based on our analysis, the correct choice is Choice 1:

y=12x+10 y = \frac{1}{2}x + 10 and y=12(x+2) y = \frac{1}{2}(x + 2)

3

Final Answer

y=12x+10 y=\frac{1}{2}x+10

y=12(x+2) y=\frac{1}{2}(x+2)

Key Points to Remember

Essential concepts to master this topic
  • Linear Form: All equations must be in y = mx + b format
  • Slope Comparison: Expand 12(x+2) \frac{1}{2}(x+2) to 12x+1 \frac{1}{2}x + 1
  • Verification: Both slopes equal 12 \frac{1}{2} with different y-intercepts confirms parallel ✓

Common Mistakes

Avoid these frequent errors
  • Assuming equations are parallel without checking slope equality
    Don't just look at similar-looking equations like y = 3x + 2 and y = 2x + 3 = they're not parallel! Different slopes (3 ≠ 2) mean different directions. Always expand all expressions first, then compare slopes exactly.

Practice Quiz

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Which statement best describes the graph below?

xy

FAQ

Everything you need to know about this question

How do I know if an equation is linear?

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A linear equation has no exponents greater than 1 on variables. Look for the form y = mx + b. If you see x2 x^2 , x3 x^3 , or fractions with x in denominators, it's not linear!

What makes two lines parallel?

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Parallel lines have identical slopes but different y-intercepts. If slopes are the same and y-intercepts are also the same, the lines are identical (same line).

Do I need to expand expressions like ½(x+2)?

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Yes, always expand first! 12(x+2) \frac{1}{2}(x+2) becomes 12x+1 \frac{1}{2}x + 1 . Only then can you clearly see the slope and y-intercept to make comparisons.

What if one equation has x² in it?

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That equation is quadratic, not linear. Since we need both equations to be linear for parallel lines, any pair with a quadratic equation cannot represent parallel lines.

Can I rearrange equations to standard form instead?

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You can, but slope-intercept form (y = mx + b) makes it much easier to compare slopes directly. Stick with this form for parallel line problems.

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