Question

6) 3 √ 20-0,5 √80+2 √ 45.

Answer 1

$3 \sqrt{20} - 0.5 \sqrt{80} + 2 \sqrt{45} = 3 \sqrt{2 {}^{2} \times 5} - 0.5 \sqrt{ {4}^{2} \times 5} + 2 \sqrt{ {3}^{2} \times 5} = 3 \times 2 \sqrt{5} - 0.5 \times 4 \sqrt{5} + 2 \times 3 \sqrt{5} = 6 \sqrt{5} - 2 \sqrt{5} + 6 \sqrt{5} = (6 - 2 + 6) \sqrt{5} = 10 \sqrt{5}$