Math, asked by pragya67, 1 year ago

7+3√5/3+√5 - 7-3√5/3-√5

Answers

Answered by DaIncredible
11
Hey friend,
Here is the answer you were looking for:
 \frac{7 + 3 \sqrt{5} }{3 +  \sqrt{5} }  -  \frac{7 - 3 \sqrt{5} }{3 -  \sqrt{5} }  \\  \\  on \: rationalizing \: we \: get \\  \\  \frac{7 + 3 \sqrt{5} }{3 +  \sqrt{5} }  \times  \frac{3 -  \sqrt{5} }{3 -  \sqrt{5} }  -  \frac{7 - 3 \sqrt{5} }{3 -  \sqrt{5} }  \times  \frac{3 +  \sqrt{5} }{3 +  \sqrt{5} }  \\  \\  using \: the \: identity \\ (a + b)(a - b) =  {a}^{2}  -  {b}^{2}  \\  \\  (\frac{7 \times 3 - 7 \times  \sqrt{5} + 3 \sqrt{5} \times 3 - 3 \sqrt{5} \times  \sqrt{5}  }{ {(3)}^{2}  -  {( \sqrt{5} )}^{2} } ) \\  - ( \frac{7 \times 3 + 7 \times  \sqrt{5}  - 3 \sqrt{5}  \times 3 - 3 \sqrt{5}  \times  \sqrt{5} }{ {(3)}^{2} -  {( \sqrt{5}) }^{2}  }  )\\  \\  =(  \frac{21 - 7 \sqrt{5} + 9\sqrt{5}   - 15}{9 - 5} ) \\  - ( \frac{21 + 7 \sqrt{5} - 9 \sqrt{5}   - 15}{9 - 5} ) \\  \\  = ( \frac{6 + 2 \sqrt{5} }{4} ) - ( \frac{6 - 2 \sqrt{5} }{4} ) \\  \\  =  \frac{6 + 2 \sqrt{5} - 6 + 2 \sqrt{5}  }{4}  \\  \\  =  \frac{2 \sqrt{5}  + 2 \sqrt{5} }{4}  \\  \\  =  \frac{4 \sqrt{5} }{4}  \\  \\  =  \sqrt{5}

Hope this helps!!!!

@Mahak24

Thanks...
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