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Solution 3.1:6d

From Förberedande kurs i matematik 1

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The problem with this expression is that the denominator contains three roots and so there is no simple way to get rid of all root signs at once; rather, we need to work step by step. In the first step, we view the numerator as (2+3)+6  and multiply the top and bottom of the fraction by the conjugate-like expression (2+3)6 . Then, at least 6  will be squared away using the formula for the difference of two squares

1(2+3)+6(2+3)6(2+3)6=(2+3)6(2+3)2(6)2=(2+3)26(2+3)6.

We expand the remaining quadratic, (2+3)2 , using the formula for the difference of two squares,

(2+3)26(2+3)6=2+36(2)2+223+(3)26=2+362+223+36=2612+36.

This expression has only a root sign in the denominator and we can then complete the calculation by multiplying top and bottom by the conjugate 26+1 ,

2612+36=2612+3626+126+1=(26)212(2+36)(26+1)=22(6)212226+21+326+3162661=46122223+2+3223+32(6)26=2412(2)23+2+2(3)22+3266=23223+2+232+3126=23(1+23)2+(22+1)3126=2372+53612.