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C1 Question

I've been trying to figure out this question on surds for half an hour

Any help?

1√28 – 2√63 +√7

Pos Rep to the best soultion

Spoiler

Reply 1

rbnphlp

Mist786

I've been trying to figure out this question on surds for half an hour

Any help?

1√28 – 2√63 +√7

Pos Rep to the best soultion

\sqrt{28}=2\sqrt{7}

similarly what is root 63

Spoiler

Can you simplify further?

Reply 2

maxfire

Make everything respect to

\sqrt 7

\sqrt 28 = 2\sqrt7

-2\sqrt 63 = -2\times3\sqrt7

so your equation would be

-6\sqrt 7 + 2\sqrt 7 + \sqrt 7

Reply 3

rushhour72

Mist786

I've been trying to figure out this question on surds for half an hour

Any help?

1√28 – 2√63 +√7

Pos Rep to the best soultion

1√28 = 1√(4 x 7) = 2√7
2√63 = 2√(7 x 9) = 6√7
√7=√7
so 1√28 – 2√63 +√7 = 2√7-6√7+√7= -3√7

Reply 4

DickDastardly

how do you peeps get these maths symbols in your posts?

Reply 5

Mist786

DickDastardly

how do you peeps get these maths symbols in your posts?

I copy the symbol from microsoft word :biggrin:

Reply 6

taylorrrr96

Its like getting all fractions with the same denominator. First simplify the surds down so all have root 7 then do what you like with them.

Reply 7

Mist786

rushhour72

1√28 = 1√(4 x 7) = 2√7
2√63 = 2√(7 x 9) = 6√7
√7=√7
so 1√28 – 2√63 +√7 = 2√7-6√7+√7= -3√7

How do you get -3?
Isn't 2-6=-4

Reply 8

jakash

DickDastardly

how do you peeps get these maths symbols in your posts?

Using this thing (I don't know what its properly called) called latex. Learn about it here: http://www.thestudentroom.co.uk/wiki/LaTex

Reply 9

rushhour72

Mist786

How do you get -3?
Isn't 2-6=-4

cos u gotta add the √7 to the -4√7

Reply 10

LUFCMatt

1\sqrt{28}-2\sqrt63 +\sqrt7[br][br][br]Split into [1\sqrt{28}] and [2\sqrt63] and [\sqrt7][br][br][br]1\sqrt28 = 1\sqrt4\sqrt7 = 1\times2\sqrt7 = 2\sqrt7[br][br][br]2\sqrt63 = 2\sqrt9\sqrt7 = 2\times3\sqrt7 = 6\sqrt7[br][br][br]\sqrt7 = \sqrt7[br][br][br]Now put the rewritten values back into the original equation[br][br][br]2\sqrt7-6\sqrt7+\sqrt7 = -3\sqrt7

Hope that's clear enough!

Reply 11

Mist786

Thanks for the help x

Reply 12

rushhour72

Mist786

Thanks for the help x

so wheres our rep? x

Reply 13

Mist786

rushhour72

so wheres our rep? x

You seem very eagar for rep :p:

You'll have wait as I have to give rep to others
Dont worry, you will get rep sometime this week
Oh, if I forget then PM me x

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