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# If x = √25 – √21, y = √37 – √33 and z = 2( √7 − √6) then which of the

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Re: If x = √25 – √21, y = √37 – √33 and z = 2( √7 − √6) then which of the [#permalink]
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$$√25 – √21 *\frac{√25 + √21}{√25 + √21}$$
$$(a-b)*(a+b)=a^2-b^2$$

$$√25 – √21= \frac{25-21}{√25 + √21}$$
$$√25 – √21=\frac{4}{√25 + √21}$$

Shrey9 wrote:
Where do you get 4 from in X and y ?

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Re: If x = √25 – √21, y = √37 – √33 and z = 2( √7 − √6) then which of the [#permalink]
nick1816 wrote:
$$√25 – √21 *\frac{√25 + √21}{√25 + √21}$$
$$(a-b)*(a+b)=a^2-b^2$$

$$√25 – √21= \frac{25-21}{√25 + √21}$$
$$√25 – √21=\frac{4}{√25 + √21}$$

Shrey9 wrote:
Where do you get 4 from in X and y ?

Posted from my mobile device

Hello nick1816

How did you find the difference between y and z?, they are very close, about .50

Kind regards!
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Re: If x = √25 – √21, y = √37 – √33 and z = 2( √7 − √6) then which of the [#permalink]
y=x^(1/2)

keeping the difference between x constant,i.e., 4, the value of dy is decreases as x increases

Hence, x>z>y
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Re: If x = 25 21, y = 37 33 and z = 2( 7 6) then which of the [#permalink]
leehaorobert wrote:
x = 4/(√25+√21)
y = 4/(√37+√33)
z = 2/(√7+√6) = 4/(√28+√24)
so x>z>y, choose C

­How did you derive z = 2/(√7+√6) = 4/(√28+√24) this?
Re: If x = 25 21, y = 37 33 and z = 2( 7 6) then which of the [#permalink]
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