a = [tex] \frac{4}{ \sqrt{3} -1} = \frac{4( \sqrt{3}+1 )}{( \sqrt{3} +1)( \sqrt{3}-1) } } = \frac{4( \sqrt{3}+1 )}{ \sqrt{3} ^{2}- 1^{2} } =[/tex] [tex] \frac{4( \sqrt{3}+1 )}{3-1} = \frac{4( \sqrt{3}+1 )}{2} = [/tex] 2(√3+1) = 2√3 + 2
b = 4 - √6 · √2 = 4 - √12 = 4 - 2√3
ma = (a+b) : 2 = (2√3+2+4-2√3) : 2 = (2+4) : 2 = 6 : 2 = 3
Sper ca te-am ajutat :D
