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

Question

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

Video Solution

Solution Steps

00:00 Find the largest X
00:03 First let's find X from section 1
00:13 Let's use the shortened multiplication formulas to open the parentheses
00:34 Square root equals the number itself
00:37 Calculate 4 squared
00:41 Isolate X
00:46 This is the value of X from section 1
00:53 Now let's calculate X from section 2
00:57 Square it to eliminate the root
01:07 This is X from section 2
01:11 We can see that the solution for X is equal for both sections
01:15 And this is the solution to the question

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 .

Answer

2=1