Identify the Function's Graph Passing Through Point (2,8)

Function Identification with Point Verification

Choose the graph of the function that passes through the point (2,8) (2,8)

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find which line the point is on
00:03 In each point, the left number represents the X-axis and the right number represents Y
00:06 Let's substitute the point in each line equation and see if it's possible
00:12 It's not possible, therefore the point is not on this line
00:16 Let's use the same method and find which line the point is on
00:19 Let's substitute in this line and check if it's possible
00:24 It's possible, therefore the point is on this line
00:29 Let's substitute in this line and check if it's possible
00:33 It's not possible, therefore the point is not on this line
00:36 Let's substitute in this line and check if it's possible
00:41 It's not possible, therefore the point is not on this line
00:44 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 graph of the function that passes through the point (2,8) (2,8)

2

Step-by-step solution

To solve this problem, we will check which of the given functions passes through the point (2,8)(2, 8) by substituting x=2x = 2 and verifying if the resulting yy-value is 8.

  • Check each function:
  • 1. For y=x4y = \frac{x}{4}:

Substitute x=2x = 2:
y=24=12y = \frac{2}{4} = \frac{1}{2}
This does not satisfy the condition y=8y = 8.

  • 2. For y=4xy = 4x:

Substitute x=2x = 2:
y=4×2=8y = 4 \times 2 = 8
This satisfies the condition y=8y = 8.

  • 3. For y=4xy = -4x:

Substitute x=2x = 2:
y=4×2=8y = -4 \times 2 = -8
This does not satisfy the condition y=8y = 8.

  • 4. For y=x4y = x^4:

Substitute x=2x = 2:
y=24=16y = 2^4 = 16
This does not satisfy the condition y=8y = 8.

Therefore, the only function that passes through the point (2,8)(2, 8) is y=4xy = 4x.

Thus, the solution to the problem is y=4xy = 4x.

3

Final Answer

y=4x y=4x

Key Points to Remember

Essential concepts to master this topic
  • Point Substitution: Replace x with given value to find y-coordinate
  • Technique: Test each function: substitute x = 2, check if y = 8
  • Check: Only y = 4x gives 4(2) = 8, matching the point ✓

Common Mistakes

Avoid these frequent errors
  • Choosing functions that look similar without testing
    Don't pick y = -4x just because it has the same coefficient as y = 4x = wrong sign gives -8 instead of 8! The negative makes all the difference. Always substitute the x-value and verify the y-value matches exactly.

Practice Quiz

Test your knowledge with interactive questions

Which statement best describes the graph below?

xy

FAQ

Everything you need to know about this question

What does it mean for a function to pass through a point?

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When a function passes through a point like (2,8), it means that when you substitute x = 2 into the function, you get y = 8. The point satisfies the equation!

Do I need to test all the answer choices?

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It's always safer to test each option! Even if you find one that works, checking the others helps you understand why they're wrong and builds confidence in your answer.

What if more than one function passes through the point?

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In this type of problem, only one function should pass through the given point. If you find multiple answers, double-check your substitution calculations!

Why didn't y=x4 y = x^4 work even though it involves the number 4?

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Don't be fooled by similar numbers! y=x4 y = x^4 means x to the fourth power, so 24=16 2^4 = 16 , not 8. Always calculate carefully!

How can I avoid calculation errors when substituting?

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Write each step clearly:

  • State the function
  • Show the substitution: "Let x = 2"
  • Calculate step-by-step
  • Compare your result to the required y-value

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