Question

Cum se face calculul?
(2-√3) la a doua -(-4-5)

Answer 1

$(2 - \sqrt{3})^{2} - ( - 4 \sqrt{5} )$
Cand ai o suma sau o diferenta la patrat si nu o poti calcula efectiv, folosesti formula binomului
$( x - y)^{2} = {x}^{2} - 2xy + {y}^{2}$
$(2 - \sqrt{3})^{2} = {2}^{2} - 2 \times 2 \times \sqrt{3} + \sqrt{3}^{2} \\ = 4 - 4 \sqrt{3} + 3$
$4 - 4 \sqrt{3} + 3 - ( - 4 \sqrt{5} ) = \\ 4 - 4 \sqrt{ 3} + 3 + 4 \sqrt{5} \\ 7 - 4 \sqrt{3} + 4 \sqrt{5}$