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Maths question method

Hi everyone, I have to express the following in the form of a+b square root c

e.g. A) Ill use letters instead of the numbers as i want to work it out myself i just need the method.. (a - squareroot b ) to the power of 2
just expand out brackets?

e.g. (c + d)^2 = c^2 + 2cd + d^2
Original post by harry218
Hi everyone, I have to express the following in the form of a+b square root c

e.g. A) Ill use letters instead of the numbers as i want to work it out myself i just need the method.. (a - squareroot b ) to the power of 2


Write is as (a-rootb) x (a-rootb) then expand ( multiply both things in left bracket by both things in the right.
Ohh that is so simply thank you! now how about for A/B-rootC ?
Original post by harry218
Ohh that is so simply thank you! now how about for A/B-rootC ?


Is (b- root c) all on the bottom if the fraction? Or just the b?
(edited 9 years ago)
to express (A divided by (B - (root C))) in the form of a + b squareroot c.. if that makes more sense to you??
Original post by harry218
to express (A divided by (B - (root C))) in the form of a + b squareroot c.. if that makes more sense to you??


What do you think it is?
Original post by harry218
to express (A divided by (B - (root C))) in the form of a + b squareroot c.. if that makes more sense to you??


Yeah. Multiply the fraction by (b+rootc)/(b+rootc)

(a-b)(a+b)=a^2-b^2 so doing this gets rid of any roots on the bottom of the fraction
I initially treated it like a surd however came to realise i was doing it wrong cambo. ok thank you underthecandle! great help!

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