Can someone please help with this math question:)


Can someone please help with this math question:)

kimmy6973 kimmy6973    3   14.02.2022 03:20    10

Answers
dakotagorski05 dakotagorski05  14.02.2022 03:20

Solution:

The rationalisation factor for \frac{1}{ a -  \sqrt{b}  } is a + \sqrt{b}

So, let us apply it here.

\frac{1}{5 -  \sqrt{2} }

The rationalising factor for 5 - √2 is 5 + √2.

Therefore, multiplying and dividing by 5 + √2, we have

=  \frac{1}{5 -  \sqrt{2} }  \times  \frac{5 +  \sqrt{2} }{5 +  \sqrt{2} }  \\  =  \frac{5 +  \sqrt{2} }{(5 -  \sqrt{2})(5 +  \sqrt{2} ) }  \\  =  \frac{5 +  \sqrt{2} }{ {(5)}^{2} - ( \sqrt{2})^{2}   }  \\  =  \frac{5 +  \sqrt{2} }{25 -  2}  \\  =  \frac{5 +  \sqrt{2} }{23}

\frac{5 +  \sqrt{2} }{23}

Hope you could understand.

If you have any query, feel free to ask.

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bankskry bankskry  14.02.2022 03:20

\frac{5+\sqrt{2} }{23}

Step-by-step explanation:

To rationalise the denominator, multiply the numerator and denominator by the conjugate of the denominator.

the conjugate of 5 - \sqrt{2} is 5 + \sqrt{2} , then

= \frac{1(5+\sqrt{2}) }{(5-\sqrt{2})(5+\sqrt{2})  } ← expand denominator using aFOIL

= \frac{5+\sqrt{2} }{25-2}

= \frac{5+\sqrt{2} }{23}

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