Square Root Equations: Solve (√x+4)(√x-4)=0 and √x=4 for Largest X

Square Root Equations with Product Form

Solve each equation separately and find which x is the largest.

  1. (x+4)(x4)=0 (\sqrt{x}+4)(\sqrt{x}-4)=0

  2. x=4 \sqrt{x}=4

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:14 Let's find the largest value of X.
00:18 First, we'll determine X from section one.
00:27 Let's use the multiplication formulas to simplify the expression.
00:48 Remember, the square root squared is just the number.
00:52 Now, calculate four squared.
00:56 Isolate X to find its value.
01:00 This is the value of X from section one.
01:07 Next, let's find X from section two.
01:11 Square the expression to remove the root.
01:21 Here's X from section two.
01:25 We see that the X values are equal in both sections.
01:30 And that's how we solve this question!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve each equation separately and find which x is the largest.

  1. (x+4)(x4)=0 (\sqrt{x}+4)(\sqrt{x}-4)=0

  2. x=4 \sqrt{x}=4

2

Step-by-step solution

To solve these equations, we'll follow these steps:

  • Step 1: Solve (x+4)(x4)=0 (\sqrt{x}+4)(\sqrt{x}-4)=0
  • Step 2: Solve x=4 \sqrt{x}=4
  • Step 3: Compare both solutions to find the largest value of x x

Let's work through each step:

Step 1: For the equation (x+4)(x4)=0 (\sqrt{x}+4)(\sqrt{x}-4)=0 , note that it is in the form of a difference of squares: a2b2=(ab)(a+b)=0 a^2 - b^2 = (a-b)(a+b) = 0 . Here, a=x a = \sqrt{x} and b=4 b = 4 , giving:

a2b2=(x)242=x16=0 a^2 - b^2 = (\sqrt{x})^2 - 4^2 = x - 16 = 0

This simplifies to x16=0 x - 16 = 0 , meaning x=16 x = 16 .

Step 2: For the equation x=4 \sqrt{x} = 4 , squaring both sides yields:

(x)2=42 (\sqrt{x})^2 = 4^2 x=16 x = 16

Step 3: Now that both equations result in x=16 x = 16 , there is only one unique solution. Comparing the single value from each equation, x=16 x = 16 is the largest.

Therefore, the largest x x is x=16 x = 16 .

3

Final Answer

2=1

Key Points to Remember

Essential concepts to master this topic
  • Domain Rule: Square root requires x ≥ 0 for real solutions
  • Zero Product: If (a)(b) = 0, then a = 0 or b = 0
  • Check: Substitute x = 16: 16=4 \sqrt{16} = 4 in both equations ✓

Common Mistakes

Avoid these frequent errors
  • Ignoring domain restrictions
    Don't solve algebraically without checking x ≥ 0 first = negative solutions that don't work! Square roots are only defined for non-negative numbers in real solutions. Always verify your answer satisfies the domain restriction.

Practice Quiz

Test your knowledge with interactive questions

Solve:

\( (2+x)(2-x)=0 \)

FAQ

Everything you need to know about this question

Why does (x+4)(x4)=0 (\sqrt{x}+4)(\sqrt{x}-4)=0 give the same answer as x=4 \sqrt{x}=4 ?

+

The first equation uses the zero product property. Since x+4 \sqrt{x}+4 is always positive (square roots can't be negative), only x4=0 \sqrt{x}-4=0 can equal zero, giving x=4 \sqrt{x}=4 !

What if I got x = -16 as a solution?

+

That's impossible! Remember that x \sqrt{x} requires x ≥ 0. Negative values under the square root don't give real solutions. Always check your domain!

How do I solve the zero product form?

+

Set each factor equal to zero: x+4=0 \sqrt{x}+4=0 or x4=0 \sqrt{x}-4=0 . The first gives x=4 \sqrt{x}=-4 (impossible), so only x=4 \sqrt{x}=4 works.

Why is the answer "2 = 1" instead of just x = 16?

+

The question asks to compare which x is largest between the two equations. Since both equations give x = 16, they're equal! The answer "2 = 1" means equation 2 equals equation 1 in terms of their solutions.

Can I use the difference of squares formula here?

+

Yes! (x+4)(x4) (\sqrt{x}+4)(\sqrt{x}-4) equals (x)242=x16 (\sqrt{x})^2 - 4^2 = x - 16 . Setting this equal to zero gives x = 16 directly.

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Short Multiplication Formulas questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations