Question

$\sqrt{20} -2\sqrt{45}$

Answer 1

$-4\sqrt{5}$

Explicação passo-a-passo:

$\sqrt{20} -2\sqrt{45}$

$=\sqrt{4.5} -2\sqrt{9.5}$

$=\sqrt{4}.\sqrt{5} -2\sqrt{9}.\sqrt{5}$

$=2\sqrt{5} - 2.3\sqrt{5}$

$=2\sqrt{5} -6\sqrt{5}$

$=-4\sqrt{5}$

Answer 2

Oie, Tudo Bom?

$= \sqrt{20} - 2 \sqrt{45}$

$= \sqrt{2 {}^{2} \: . \: 5 } - 2 \sqrt{3 {}^{2} \: . \: 5 }$

$= \sqrt{2 {}^{2} } \sqrt{5} - 2 \sqrt{3 {}^{2} } \sqrt{5}$

$= 2 \sqrt{5} - 2 \: . \: 3 \sqrt{5}$

$= 2 \sqrt{5} - 6 \sqrt{5}$

$= (2 - 6) \sqrt{5}$

$\boxed { = - 4 \sqrt{5} }$

Att. Makaveli1996