15 / √31 – 4 can someone just solve this for me please PLEASE ANSWER ONLY IF YOU ARE SURE else I am out of the class

Question

15 / √31 – 4
can someone just solve this for me please
PLEASE ANSWER ONLY IF YOU ARE SURE else I am out of the class

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Trung Dũng 3 years 2021-07-31T05:35:31+00:00 1 Answers 44 views 0

Answers ( )

  1. thienan
    0
    2021-07-31T05:37:13+00:00
    Reply

    Answer:

    \frac{15}{ \sqrt{31} - 4}} = \sqrt{31} + 4

    Step-by-step explanation:

    \frac{15}{\sqrt{31} - 4}\\\\=\frac{15}{\sqrt{31} - 4} \times \frac{\sqrt{31} + 4}{\sqrt{31}+ 4} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ rationalizing \ the \ denominator \ ]\\\\=\frac{15( \sqrt{31} + 4 )}{(\sqrt{31})^2 - (4)^2} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ (a-b)(a+b) = a^2 - b^2 \ ]\\\\=\frac{15 ( \sqrt{31} + 4)}{31 - 16}\\\\=\frac{15 (\sqrt{31} + 4)}{15}\\\\= \sqrt{31} + 4

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