Is the Linear Function y = x - 1 Increasing or Decreasing?

Linear Functions with Slope Analysis

Given the following function:

y=x1 y=x-1

Is the function increasing or decreasing?

–2–2–2222444–2–2–2000

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Is the function increasing or decreasing?
00:04 The function equation according to the given data
00:12 The function slope is positive according to the given data
00:15 When the function slope is positive, the function is increasing
00:18 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

Given the following function:

y=x1 y=x-1

Is the function increasing or decreasing?

–2–2–2222444–2–2–2000

2

Step-by-step solution

To determine if the function y=x1 y = x - 1 is increasing or decreasing, we will analyze its slope:

  • Step 1: Identify the function as a linear function in the form y=mx+b y = mx + b where m=1 m = 1 and b=1 b = -1 .

  • Step 2: Recall that for a linear function, if the slope m>0 m > 0 , the function is increasing. Conversely, if m<0 m < 0 , it is decreasing.

  • Step 3: Calculate the slope: m=1 m = 1 . Since m=1 m = 1 is positive, this means the function is increasing.

The behavior of the function depends on the sign of the slope. Here, because the slope is positive, the function y=x1 y = x - 1 increases as x x increases across its entire domain.

Therefore, the function is Increasing.

3

Final Answer

Increasing

Key Points to Remember

Essential concepts to master this topic
  • Rule: Positive slope means increasing function across entire domain
  • Technique: Identify slope m = 1 from y=x1 y = x - 1
  • Check: Pick two points: when x = 0, y = -1; when x = 2, y = 1 ✓

Common Mistakes

Avoid these frequent errors
  • Confusing y-intercept with slope
    Don't think the function is decreasing because b = -1 is negative! The y-intercept doesn't determine if a function increases or decreases. Always look at the coefficient of x (the slope) to determine the function's behavior.

Practice Quiz

Test your knowledge with interactive questions

Is the function in the graph decreasing? yx

FAQ

Everything you need to know about this question

How can I tell if a linear function is increasing or decreasing just by looking at the equation?

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Look at the coefficient of x (the slope). If it's positive, the function is increasing. If it's negative, the function is decreasing. In y=x1 y = x - 1 , the coefficient is +1, so it's increasing!

Does the y-intercept affect whether a function is increasing or decreasing?

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No! The y-intercept only tells you where the line crosses the y-axis. It doesn't affect the direction of the line. Only the slope determines if the function increases or decreases.

What if the slope is zero?

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If the slope is zero, the function is neither increasing nor decreasing - it's constant! The graph would be a horizontal line where y stays the same for all x values.

How can I verify my answer using the graph?

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Look at the line from left to right. If it goes upward, it's increasing. If it goes downward, it's decreasing. The graph shows the line going up as you move from left to right!

Can a linear function be both increasing and decreasing?

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Never! A linear function has the same slope everywhere, so it's either always increasing, always decreasing, or always constant. It can't change its behavior like curved functions do.

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