Math  /  Algebra

QuestionAssignment Active
Analyzing a Solution
A student concluded that the solution to the equation 2x+1+3=0\sqrt{2 x+1}+3=0 is x=4x=4.
Do you agree? Explain why or why not. \square DONE

Studdy Solution

STEP 1

What is this asking? Is x=4x = 4 the correct solution to the equation 2x+1+3=0\sqrt{2x + 1} + 3 = 0? Watch out! Square roots can be tricky!
Remember a square root can't be negative.

STEP 2

1. Isolate the Square Root
2. Square Both Sides
3. Solve for xx
4. Check the Solution

STEP 3

Let's **isolate** that square root term!
We want to get 2x+1\sqrt{2x + 1} all by itself on one side of the equation.
Our equation is 2x+1+3=0\sqrt{2x + 1} + 3 = 0.
To do this, we'll **subtract** 33 from both sides of the equation.
This is like carefully removing a weight from a balanced scale – we have to do it on both sides to keep things equal!

STEP 4

Subtracting 33 from both sides gives us: 2x+1+33=03 \sqrt{2x + 1} + 3 - 3 = 0 - 3 2x+1=3 \sqrt{2x + 1} = -3 Now our square root is nicely isolated!

STEP 5

To get rid of the square root, we're going to **square both sides** of the equation.
Think of it like unwrapping a present – squaring a square root removes the "root" and leaves us with what's inside.

STEP 6

Squaring both sides gives us: (2x+1)2=(3)2 (\sqrt{2x + 1})^2 = (-3)^2 2x+1=9 2x + 1 = 9 Look at that, no more square roots!

STEP 7

Now, we just need to **solve for** xx.
First, let's **subtract** 11 from both sides: 2x+11=91 2x + 1 - 1 = 9 - 1 2x=8 2x = 8

STEP 8

Next, we'll **divide** both sides by 22 to get xx all alone: 2x2=82 \frac{2x}{2} = \frac{8}{2} x=4 x = 4 So, we get x=4x = 4, just like the student did!
But wait, there's one more crucial step...

STEP 9

We *always* need to **check our solution** with square root equations.
Sometimes, we get solutions that don't actually work in the original equation.
These are called **extraneous solutions**.
Let's plug x=4x = 4 back into the original equation: 2(4)+1+3=0 \sqrt{2(4) + 1} + 3 = 0 8+1+3=0 \sqrt{8 + 1} + 3 = 0 9+3=0 \sqrt{9} + 3 = 0 3+3=0 3 + 3 = 0 6=0 6 = 0 Uh oh!
That's definitely not true!

STEP 10

x=4x = 4 is *not* the correct solution.
In fact, there's no solution to this equation!
We found that when we plugged x=4x = 4 back in, we got a statement that isn't true.
This means there's no value of xx that will satisfy the original equation.

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