Linear Function Graph: Finding Line Through Points (1,5) and (7,1)

Slope Analysis with Negative Values

The graph of the linear function passes through the points B(1,5),A(7,1) B(1,5),A(7,1)

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Determine the type of slope
00:04 Find the slope using 2 points
00:15 Use the formula to find the slope using 2 points
00:24 Substitute appropriate values according to the given data and solve to find the slope
00:41 The slope is negative, therefore the function is decreasing
00:49 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

The graph of the linear function passes through the points B(1,5),A(7,1) B(1,5),A(7,1)

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given points B(1,5) B(1, 5) and A(7,1) A(7, 1) .
  • Step 2: Calculate the slope using the formula m=y2y1x2x1 m = \frac{y_2 - y_1}{x_2 - x_1} .
  • Step 3: Interpret the result to determine if the function is increasing, decreasing, or constant.

Now, let's work through each step:
Step 1: The given points are B(1,5) B(1, 5) and A(7,1) A(7, 1) .
Step 2: We calculate the slope as follows: m=1571=46=23 m = \frac{1 - 5}{7 - 1} = \frac{-4}{6} = -\frac{2}{3} Step 3: The slope m=23 m = -\frac{2}{3} is negative, indicating that the function decreases as x x increases.

Therefore, since the slope is negative, the function is a decreasing function.

The correct choice is the first option: Decreasing function.

3

Final Answer

Decreasing function

Key Points to Remember

Essential concepts to master this topic
  • Slope Formula: Use m=y2y1x2x1 m = \frac{y_2 - y_1}{x_2 - x_1} for any two points
  • Calculate: m=1571=46=23 m = \frac{1-5}{7-1} = \frac{-4}{6} = -\frac{2}{3}
  • Verify: Negative slope means function decreases as x increases ✓

Common Mistakes

Avoid these frequent errors
  • Confusing coordinate order when calculating slope
    Don't mix up (x₁,y₁) and (x₂,y₂) when substituting = wrong sign! This changes positive slopes to negative or vice versa. Always keep coordinates paired: if you use x₂ - x₁ in denominator, use y₂ - y₁ in numerator.

Practice Quiz

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For the function in front of you, the slope is?

XY

FAQ

Everything you need to know about this question

What does a negative slope really mean?

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A negative slope means the line goes downward from left to right. As x-values increase, y-values decrease. Think of walking downhill!

Does it matter which point I call (x₁,y₁)?

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No! You can choose either point as your starting point. Just make sure to stay consistent - if B(1,5) is (x₁,y₁), then A(7,1) must be (x₂,y₂).

How do I know if a function is increasing or decreasing?

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  • Positive slope: Function is increasing
  • Negative slope: Function is decreasing
  • Zero slope: Function is constant

What if I get a fraction for the slope?

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That's completely normal! Slopes can be whole numbers, fractions, or decimals. Just simplify the fraction if possible. Here, 46=23 -\frac{4}{6} = -\frac{2}{3} .

Can I check my slope calculation?

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Yes! Plot the points and see if your line makes sense. With slope 23 -\frac{2}{3} , for every 3 units right, the line goes 2 units down.

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