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ex 3 
aduceti la o forma mai simpla 
a)[tex]5 \sqrt{2} + 2\sqrt{32} - \sqrt{98} [/tex]
b)[tex]( \sqrt5} - \sqrt3} ) ^{2} [/tex]
d)[tex] \sqrt{5- \sqrt21{} } * \sqrt{5+ \sqrt{21} } [/tex]
e)[tex]( 4\sqrt{3} + \sqrt{27} )* \sqrt{3} [/tex]


Răspuns :

a) [tex]5 \sqrt{2} +8 \sqrt{2} -7 \sqrt{2} = 13 \sqrt{2} -7 \sqrt{2} = 6 \sqrt{2} [/tex]
b) [tex]5-2* \sqrt{5} * \sqrt{3} + 3 = 8-2 \sqrt{8} [/tex]
e)[tex](4 \sqrt{3} + 3 \sqrt{3} ) * \sqrt{3} = 7 \sqrt{3} * \sqrt{3} = 7*3=21 [/tex]
d)[tex] a^{2} - b^{2} =(a-b)(a+b) ---> asta e formula [/tex]
a)2√32=2√2²√2²√2=2·2·2√2=8√2
√98=√7²√2=7√2
=5√2+8√2-7√2=13√2-7√2==6√2
b)(√5-√3)²=√5²-√5√3-√5√3+√3²=5-√15-√15+3=8-2√15=2(4-√15)
c))=(√5-√√21)(√5+√√21)=√5²+√5√√21-√5√√21+√√21²=
5+√21
d)√27=√3²√3=3√3
(4√3+3√3)·√3=7√3·√3=7·√3²=7·3=21