Question

efetue as multiplicações a) √6 x √3 b) 3√7 x 2√21 x 4√6 c) √2 x √9 d) 3√8 x 2√10 e) - 2√7 x 3√14

Answer 1

a)
= √6 x √3  = √18 = √9.√2 = 3√2


b)
= 3√7 x 2√21 x 4√6

= 3√7 .2√7 .   √3 . 4√3.√2

= 3.2.√7.√7.  √3.√3 . 4√2

= 6.7 . 3 . 4√2

= 42.12√2 = 504√2
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
c)
= √2 x √9   =  √2.3 = 3√2


¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
d)

= 3√8 x 2√10

= 3.√4.√2 . 2 √2.√5

= 3.2.√2. 2√2.√5

= 6√2 . 2√2. √5

= 6.2 . √2 . √2 . √5

= 12 . 2 . √5

= 24√5

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
e)
= - 2√7 x 3√14

= - 2.3 √7 . √14

= - 6 . √7 . √7 . √2

= - 6.7. √2

= - 42√2