Analyze the Linear Function: y=-x+1 Properties and Solution

Linear Functions with Parallel Line Properties

Choose the correct answer for the function.

y=x+1 y=-x+1

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find the slope of the graph
00:04 Any number multiplied by 1 is always equal to itself
00:08 The coefficient of X is the slope of the graph
00:12 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

Choose the correct answer for the function.

y=x+1 y=-x+1

2

Step-by-step solution

Let's start with option A

In a linear function, to check if the functions are parallel, you must verify if their slope is the same.

y = ax+b

The slope is a

In the original formula:

 y = -x+1

The slope is 1

In option A there is no a at all, which means it equals 1, which means the slope is not the same and the option is incorrect.

 

Option B:

To check if the function passes through the points, we will try to place them in the function:

-1 = -(-2)+1

-1 = 2+1

-1 = 3

The points do not match, and therefore the function does not pass through this point.

 

Option C:

We rearrange the function, in a way that is more convenient:

y = -1-x

y = -x-1

You can see that the slope in the function is the same as we found for the original function (-1), so this is the solution!

 

Option D:

When the slope is negative, the function is decreasing, as the slope is -1, the function is negative and this answer is incorrect.

3

Final Answer

The graph is parallel to the graph of function

y=1x y=-1-x

Key Points to Remember

Essential concepts to master this topic
  • Slope Rule: Parallel lines have identical slopes for linear functions
  • Technique: Compare y=x+1 y = -x + 1 with y=x1 y = -x - 1 slopes
  • Check: Substitute point coordinates: 1=(2)+1=3 -1 = -(-2) + 1 = 3 fails ✓

Common Mistakes

Avoid these frequent errors
  • Confusing slope identification in different forms
    Don't assume y = -1 - x has slope -1! This equals y = -x - 1 where slope is -1, not +1. Students mix up the coefficient of x when terms are rearranged. Always rewrite in standard y = mx + b form first.

Practice Quiz

Test your knowledge with interactive questions

What is the solution to the following inequality?

\( 10x-4≤-3x-8 \)

FAQ

Everything you need to know about this question

How do I find the slope when the equation looks different?

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Always rewrite in standard form y=mx+b y = mx + b first! For example, y=1x y = -1 - x becomes y=x1 y = -x - 1 , so the slope is -1.

Why aren't y = -x + 1 and y = x + 1 parallel?

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Their slopes are different! The first has slope -1, the second has slope +1. Parallel lines must have exactly the same slope but different y-intercepts.

How do I check if a point lies on the line?

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Substitute the x-coordinate into the equation and see if you get the y-coordinate. For (2,1) (-2, -1) : 1=?(2)+1=3 -1 \stackrel{?}{=} -(-2) + 1 = 3 False!

What makes a function increasing or decreasing?

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Look at the slope! Positive slope = increasing function, negative slope = decreasing function. Since y=x+1 y = -x + 1 has slope -1, it's decreasing.

Can two different equations represent parallel lines?

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Yes! y=x+1 y = -x + 1 and y=1x y = -1 - x are parallel because they both have slope -1, just different y-intercepts (1 and -1).

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