Linear Function Analysis: Is y=4x-2 Rising or Falling?

Linear Functions with Slope Analysis

Given the following function:

y=4x2 y=4x-2

Is the function increasing or decreasing?

–4–4–4–2–2–2222444666–4–4–4–2–2–2222000

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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?
00:03 Function equation according to the given data
00:07 The function's slope is positive according to the given data
00:11 When the function's slope is positive, the function is increasing
00:15 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=4x2 y=4x-2

Is the function increasing or decreasing?

–4–4–4–2–2–2222444666–4–4–4–2–2–2222000

2

Step-by-step solution

To determine whether the function y=4x2 y = 4x - 2 is increasing or decreasing, we follow these steps:

  • Step 1: Identify the type of function we have. The given function is in the form of y=mx+b y = mx + b , which is a linear function.

  • Step 2: Analyze the coefficient of x x , known as the slope m m . In our function, the slope m m is 4.

  • Step 3: Understand the relationship between the slope and the rate of change. For linear functions, if the slope m m is positive, the function is increasing.

Since the slope m=4 m = 4 is positive, it means that as x x increases, y y also increases. Consequently, the function is increasing over its entire domain.

Therefore, the function y=4x2 y = 4x - 2 is Increasing.

3

Final Answer

Increasing

Key Points to Remember

Essential concepts to master this topic
  • Rule: Positive slope means increasing function throughout entire domain
  • Technique: In y=4x2 y = 4x - 2 , slope m = 4 is positive
  • Check: Test two points: when x = 0, y = -2; when x = 1, y = 2 ✓

Common Mistakes

Avoid these frequent errors
  • Confusing slope with y-intercept
    Don't look at the constant term -2 to determine increasing/decreasing = wrong answer! The y-intercept only tells you where the line crosses the y-axis. Always examine the coefficient of x (the slope) to determine if a linear function increases or decreases.

Practice Quiz

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Is the function in the graph decreasing? yx

FAQ

Everything you need to know about this question

Why does a positive slope mean the function is increasing?

+

When the slope is positive, it means that for every unit increase in x, the y-value also increases. Think of it like walking up a hill - you're going up as you move forward!

What if the slope was negative instead?

+

If the slope were negative (like y=3x+5 y = -3x + 5 ), then the function would be decreasing. As x increases, y would decrease - like walking downhill.

Does the y-intercept affect whether the function increases or decreases?

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No! The y-intercept (-2 in this case) only tells you where the line crosses the y-axis. It doesn't change the direction the line is going - that's determined entirely by the slope.

How can I visualize this on the graph?

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Look at the line from left to right. If it goes upward (rising), the function is increasing. If it goes downward (falling), it's decreasing. The steeper the line, the larger the absolute value of the slope.

Is there a quick way to remember this?

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Remember: Positive slope = going UP (increasing), Negative slope = going DOWN (decreasing). Just like the + and - signs point up and down!

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