Math, asked by emma18, 1 year ago

If a and b are rational numbers, find a and b,

* √2+√3/3√2-2√3= a+b√6
* 5+2√3/7+4√3= a+b√3

Answers

Answered by therezz
2
Answer is attached below

Hope it helps
Attachments:
Answered by DaAnonymous
4
Hey friend,
Here is the answer you were looking for:
1) \\  \frac{ \sqrt{2}  +  \sqrt{3} }{3 \sqrt{2} - 2 \sqrt{3}  }  = a + b \sqrt{6}  \\  \\ on \: rationalizing \: the \: denominator \: we \: get \\  \\  =  \frac{ \sqrt{2} +  \sqrt{3}  }{3 \sqrt{2}  - 2 \sqrt{3} }  \times  \frac{3 \sqrt{2}  + 2 \sqrt{3} }{3 \sqrt{2}  + 2 \sqrt{3} }  \\  \\ using \: the \: identity \\ (a + b)(a - b) =  {a}^{2}  -  {b}^{2}  \\  \\  =  \frac{ \sqrt{2} \times 3 \sqrt{2}  +  \sqrt{2}   \times 2 \sqrt{3} +  \sqrt{3}   \times 3 \sqrt{2}  +  \sqrt{3}  \times 2 \sqrt{3} }{ {(3 \sqrt{2}) }^{2}  -  {(2 \sqrt{3}) }^{2} }  \\  \\  =  \frac{3 \times 2 + 2 \sqrt{6} + 3 \sqrt{6}   + 2 \times 3}{18 - 12}  \\  \\  =  \frac{6 + 5 \sqrt{6}  + 6}{6}   \\  \\   \frac{12 + 5 \sqrt{6} }{6} = a + b \sqrt{6}   \\  \\   a =  \frac{12}{6}  \\  \\ a = 2 \\  \\ b =  \frac{5}{6}  \\  \\ 2) \\  \frac{5 + 2 \sqrt{3} }{7 + 4 \sqrt{3} }  = a + b \sqrt{3}  \\  \\ on \: rationalizing \: the \: denominator \: we \: get \\  \\  =  \frac{5 + 2 \sqrt{3} }{7 + 4 \sqrt{3} }  \times  \frac{7 - 4 \sqrt{3} }{7 - 4 \sqrt{3} }  \\  \\ using \: the \: identity \\ (a + b)(a - b) =  {a}^{2}  -  {b}^{2}  \\  \\  =  \frac{5 \times 7 - 5 \times 4 \sqrt{3} + 2 \sqrt{3}   \times 7 - 2 \sqrt{3}  \times 4 \sqrt{3} }{ {(7)}^{2} -  {(4 \sqrt{3} )}^{2}  }  \\  \\  =  \frac{35 - 20 \sqrt{3} + 14 \sqrt{3}   - 8 \times 3}{49 - 48}  \\  \\  =  35 - 24 - 20 \sqrt{3} + 14 \sqrt{3}  \\  \\  11 - 6 \sqrt{3}  = a + b \sqrt{3}  \\  \\ a = 11 \\  \\ b =  - 6


Hope this helps!!!!

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