4.
a)
[tex] {{( \sqrt{2} \times \sqrt{3} + \sqrt{72} \div \sqrt{3} - {( \sqrt{5}) } }^{2} \times \sqrt{6} ) }^{2} = {( \sqrt{6} + \sqrt{24} - 5 \times \sqrt{6}) }^{2} = 6 + 24 - 25 \times 6 = 6 + 24 - 150 = 30 - 150 = - 120[/tex]
b) a- varsta lui mihai
b-varsta tatalui
b=3×a
a+b=48
a+3×a=48
4×a=48
a=12 ani
