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# (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 =

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Re: (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 = [#permalink]
Kinshook wrote:
Bunuel wrote:
$$(\sqrt{12.5} + \sqrt{12.5})^2 - (\sqrt{25})^2 =$$

(A) 0
(B) 5
(C) 12.5
(D) 25
(E) 50

$$(\sqrt{12.5} + \sqrt{12.5})^2 - (\sqrt{25})^2 = 2\sqrt{12.5})^2 - 25 = (\sqrt{50})^2 -25 = 50 -25 = 25$$

IMO D

How to understand that that twice the root out of 12.5 equals 50?
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Re: (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 = [#permalink]
lacktutor wrote:
(2√12.5)^2–(√25)^2= 4*12.5–25=50-25=25

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Can you please explain why 4*12.5?
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Re: (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 = [#permalink]
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Luca1111111111111 wrote:
lacktutor wrote:
(2√12.5)^2–(√25)^2= 4*12.5–25=50-25=25

Posted from my mobile device

Can you please explain why 4*12.5?

(2√12.5)^2= (2^2)*(√12.5)^2=4*12.5=50

Hope it helps
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Re: (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 = [#permalink]
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Re: (12.5^(1/2) + 12.5^(1/2))^2 - (25^(1/2))^2 = [#permalink]
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