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Bunuel
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Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
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Formula to remember for this question \(= a^2-b^2 = (a+b)(a-b)\)

\(\frac{√3−2}{√2+1}*\frac{√2-1}{√2-1}=\frac{(√3−2)(√2-1)}{2-1}=(√3−2)(√2-1)\)

\((√3−2)(√2-1) =√2√3-√3-2√2+2=P\)

\(P-4 = √2√3-√3-2√2+2-4 = √6-√3-2√2-2 =−2√2+√6–√3–2\) (with a little rearranging you get D)
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Formula to remember for this question \(= a^2-b^2 = (a+b)(a-b)\)

\(\frac{√3−2}{√2+1}*\frac{√2-1}{√2-1}=\frac{(√3−2)(√2-1)}{2-1}=(√3−2)(√2-1)\)

\((√3−2)(√2-1) =√2√3-√3-2√2+2=P\)

\(P-4 = √2√3-√3-2√2+2-4 = √6-√3-2√2-2 =−2√2+√6–√3–2\) (with a little rearranging you get D)

WHERE DID YOU GET
√2−1√2−1 From??? Confused

Posted from my mobile device
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Peachie

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Formula to remember for this question \(= a^2-b^2 = (a+b)(a-b)\)

\(\frac{√3−2}{√2+1}*\frac{√2-1}{√2-1}=\frac{(√3−2)(√2-1)}{2-1}=(√3−2)(√2-1)\)

\((√3−2)(√2-1) =√2√3-√3-2√2+2=P\)

\(P-4 = √2√3-√3-2√2+2-4 = √6-√3-2√2-2 =−2√2+√6–√3–2\) (with a little rearranging you get D)

WHERE DID YOU GET
√2−1√2−1 From??? Confused

Posted from my mobile device


So what i did was multiplied (√2−1) to the numerator and denominator.... this does not change the equation but it helps to simplify the equation...

As a rule of thumb try eliminating the denominator when you get questions like these
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AvidDreamer09
Formula to remember for this question \(= a^2-b^2 = (a+b)(a-b)\)

\(\frac{√3−2}{√2+1}*\frac{√2-1}{√2-1}=\frac{(√3−2)(√2-1)}{2-1}=(√3−2)(√2-1)\)

\((√3−2)(√2-1) =√2√3-√3-2√2+2=P\)

\(P-4 = √2√3-√3-2√2+2-4 = √6-√3-2√2-2 =−2√2+√6–√3–2\) (with a little rearranging you get D)

WHERE DID YOU GET
√2−1√2−1 From??? Confused

Posted from my mobile device


We call it rationalization

if u have (√2 -1)/(√2+1)

them u can always multiply the Numerator and denominator by √2-1 ( same term but change the sign of one term )


award kudos if helpful
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AvidDreamer09
Formula to remember for this question \(= a^2-b^2 = (a+b)(a-b)\)

\(\frac{√3−2}{√2+1}*\frac{√2-1}{√2-1}=\frac{(√3−2)(√2-1)}{2-1}=(√3−2)(√2-1)\)

\((√3−2)(√2-1) =√2√3-√3-2√2+2=P\)

\(P-4 = √2√3-√3-2√2+2-4 = √6-√3-2√2-2 =−2√2+√6–√3–2\) (with a little rearranging you get D)

WHERE DID YOU GET
√2−1√2−1 From??? Confused

Posted from my mobile device


We call it rationalization

if u have (√2 -1)/(√2+1)

them u can always multiply the Numerator and denominator by √2-1 ( same term but change the sign of one term )


award kudos if helpful

Wow! Thank you for stating this! It's stuck in my head now! Thanks!!
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