Rationalise the denominator of 3√+7+2√5
________
3√2
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Step-by-step explanation:
7+2
5
3
To make the Denominator Rational, we need to make the √5 Rational.
We Know, a² - b² = (a+b)(a-b)
So,
Multiplying Both the Numerator and Denominator by 7 - 2√5. We get
\begin{gathered} \frac{3}{7 + 2 \sqrt{5} } \times \frac{7 - 2 \sqrt{5} }{7 - 2 \sqrt{5} } \\ = \frac{21 - 6 \sqrt{5} }{ {7}^{2} - {2 \sqrt{5} }^{2} } \\ = \frac{21 - 6 \sqrt{5} }{49 - 20} \\ = \frac{21 - 6 \sqrt{5} }{29} \end{gathered}
7+2
5
3
×
7−2
5
7−2
5
=
7
2
−2
5
2
21−6
5
=
49−20
21−6
5
=
29
21−6
5
Hope it Helps
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