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juliahamm24
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We need to find the value of (24+5[23]^1/2)^1/2 * (24-5[23]^1/2)^1/2

If we look at the expression inside the square root then we will notice that both the terms are similar but have different signs in the middle
=> They are of the form (a-b) * (a+b) and will be equal to

So you can reach (24^2 - (5[23]^1/2)^2)^1/2

Or
(24*24 - 25*23)^1/2

Here is where you can again save time and calculation if you notice the pattern that the second term is distributed around 24 and can be written as
(24^2- (24+1)*(24-1))^1/2

Which is nothing but
(24^2 - (24^2 - 1^2))^1/2

Or

(24^2-24^2+1^2)^1/2

= (1^2)^1/2 = 1
Choice D I guess

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I incorrectly answer E, my mistake was simple but easy to make.

This is an example of a^2-b^2

sqrt 24^2- 5^2 (23)
*my mistake*

I wiped the roots with the exponents and answered E HOWEVER, this is not allowed in subtraction or additoin under roots.

What you should do is solve for 24*24 and 23*25 and get 576-575=1
All of this was still under the root and the root of 1 is 1 so D is correct.
juliahamm24
What is the value of (\(\sqrt{24 + 5\sqrt{23}})(\sqrt{24 - 5 \sqrt{23}}\))?


A. 48

B. \( \sqrt{24}\)

C. \(5 \sqrt{2}\)

D. 1

E. \(24 - 5 \sqrt{23}\)
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The first thing that is significant is this questions is a form of a^2-b^2.

Put everything under 1 root (you can do this with multiplication and division but not addition and subtraction)

translate this into sqrt 24^2- (23*25)^2

solve and get 576-575=1

D
juliahamm24
What is the value of (\(\sqrt{24 + 5\sqrt{23}})(\sqrt{24 - 5 \sqrt{23}}\))?


A. 48

B. \( \sqrt{24}\)

C. \(5 \sqrt{2}\)

D. 1

E. \(24 - 5 \sqrt{23}\)
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