Răspuns:
ab+ac =20
a(b+c)=20
[tex]b + c = 3 \sqrt{18} - 2 \sqrt{8} = 3 \times 3 \sqrt{2} - 2 \times 2 \sqrt{2} = 9 \sqrt{2} - 4 \sqrt{2} = 5 \sqrt{2} \\ a(b + c) = 20 \\ a \times 5 \sqrt{2} = 20 \\ a = \frac{20}{5 \sqrt{2} } = \frac{20 \sqrt{2} }{5 \sqrt{2} \times \sqrt{2} } = \frac{20 \sqrt{2} }{10} = 2 \sqrt{2} [/tex]
