Question 75612
Combine, if possible. 
(6.) √5 - √6 + 3√5 - 2√6
=4sqrt5 - 3sqrt6
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(8.) √7 - √63
=sqrt7 - sqrt(9*7)
=sqrt7 - 3sqrt7
=-2sqrt7
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PG. 535 Multiply. Be sure to simplify any radicals in your answer. 
(26.) (3√5 + √3) (√5 + √3)
=3*5 +3sqrt15+sqrt15+3
=18 +4sqrt15
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(36.) (3√2 + 5)^2 
=(3sqrt2 + 5)(3sqrt2 + 5)
=9*2 +15sqrt2 + 15sqrt2 + 25
=43+30sqrt2
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PG. 542 Simplify. Be sure to rationalize all denominators. 
(6.) √5 / √80 
= sqrt5/sqrt(16*5)
=sqrt5 / 4(sqrt5)
=1/4
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(14.) 6 / √17
Multiply numerator  and denominator by sqrt17 to get:
=(6sqrt17)/17
=(6/17)sqrt17
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Cheers,
Stan H.