Question

Urgent dau coroana !!!!!!!!!!!

Answer 1

Explicație pas cu pas:

a)

$\sqrt{21} \cdot \sqrt{7} + \sqrt{5} \cdot \sqrt{15} = \sqrt{3 \cdot {7}^{2} } + \sqrt{3 \cdot {5}^{2}} = 7 \sqrt{3} + 5 \sqrt{3} = 12 \sqrt{3}$

b)

$\sqrt{14} \cdot \sqrt{7} - \sqrt{10} \cdot \sqrt{5} = \sqrt{2 \cdot {7}^{2} } - \sqrt{2 \cdot {5}^{2}} = 7 \sqrt{2} - 5 \sqrt{2} = 2 \sqrt{2}$

c)

$( - \sqrt{10}) \cdot \sqrt{5} + \sqrt{14} \cdot \sqrt{7} = - \sqrt{2 \cdot {5}^{2} } + \sqrt{2 \cdot {7}^{2}} = - 5\sqrt{2} + 7 \sqrt{2} = 2 \sqrt{2}$

d)

$\sqrt{10} \cdot \sqrt{2} - \sqrt{15} \cdot ( - \sqrt{3}) = \sqrt{ {2}^{2} \cdot 5} + \sqrt{ {3}^{2} \cdot 5} = 2 \sqrt{5} + 3 \sqrt{5} = 5 \sqrt{5}$