Solve for X in y=x²: Finding X-Coordinates When y=8

What is the value of X for the function?

y=x2 y=x^2

of the point y=8 y=8 ?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Set up and solve
00:06 Substitute appropriate values according to the given data, and solve for X
00:23 Extract root
00:37 When extracting a root there are 2 solutions, positive and negative
00:42 Factor 8 into factors 4 and 2
00:48 Break down the root into 2 roots
00:52 Calculate root 4
00:56 And this is the solution to the problem

Step-by-step written solution

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1

Understand the problem

What is the value of X for the function?

y=x2 y=x^2

of the point y=8 y=8 ?

2

Step-by-step solution

The problem requires us to find the value of x x for the function y=x2 y = x^2 when y=8 y = 8 .

Let's solve this step-by-step:

  • Step 1: Set up the equation based on the given function:
     y=x2\ y = x^2 becomes  x2=8\ x^2 = 8 .
  • Step 2: Solve for x x by taking the square root of both sides:

Since  x2=8\ x^2 = 8 , we take the square root of both sides to find x x :

x=±8 x = \pm\sqrt{8}

Step 3: Simplify the square root:

The square root of 8 can be simplified to  8=4×2=42=22\ \sqrt{8} = \sqrt{4 \times 2} = \sqrt{4} \cdot \sqrt{2} = 2\sqrt{2} .

Thus,  x=±22\ x = \pm 2\sqrt{2} .

Therefore, the solution is x=±22 x = \pm 2\sqrt{2} , which corresponds to choice 4.

3

Final Answer

x=±22 x=\pm2\sqrt{2}

Practice Quiz

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What is the value of y for the function?

\( y=x^2 \)

of the point \( x=2 \)?

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