Math, asked by kaveriappan, 1 year ago

find the sq root of 9-4√5 urgent please no spam

Answers

Answered by shadowsabers03

$9 - 4\sqrt{5} \\ \\ = 4 + 5 - 4\sqrt{5} \\ \\ = 2^2 + (\sqrt{5})^2 - (2 \times 2 \times \sqrt{5}) \\ \\ = (2 - \sqrt{5})^2 \\ \\ \\ \therefore \sqrt{9 - 4\sqrt{5}} = 2 - \sqrt{5}$

$9 - 4\sqrt{5} \\ \\ = 4 + 5 - 4\sqrt{5} \\ \\ = (- 2)^2 + (\sqrt{5})^2 + (2 \times - 2 \times \sqrt{5}) \\ \\ = (- 2 + \sqrt{5})^2 \\ \\ = (\sqrt{5} - 2)^2 \\ \\ \\ \therefore \sqrt{9 - 4\sqrt{5}} = \sqrt{5} - 2$

∴ There are two answers.

Hope this may be helpful.

Please mark my answer as the brainliest if this may be helpful.

Thank you. Have a nice day.

kaveriappan: thanks

shadowsabers03: Thank you for marking my answer as the brainliest.

Answered by ankita3730

hope this may help you

Attachments:

shadowsabers03: Sorry, I can't understand or read this due to handwriting.

kaveriappan: no it is well and good

shadowsabers03: Hey, the steps are right and the right answer is gotten. But the answer written is wrong.

shadowsabers03: First said about a - b. If a = 5^1/2(means square root 5), then we get b = 2. Then a - b = 5^1/2 - 2. If a = - 5^1/2, then we get b = -2. Then a - b = - 5^1/2 - (-2) = - 5^1/2 + 2 = 2 - 5^1/2. Both are correct.

shadowsabers03: Ankita, you got the right. BUT YOU WROTE THE ANSWER AS 'A + B' INSTEAD OF

shadowsabers03: 'A - B'. THAT WAS THE MISTAKE.

ankita3730: yes Sanjeev , It's my fault, actually I was in a great hurry while solving this question

shadowsabers03: Oh, okay.

shadowsabers03: I didn't remember that any square has two square roots. I remembered that by your answer, Ankita. So I edited my answer.

ankita3730: oh

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