Cho hình vẽ sau:

Em hãy chọn khẳng định đúng nhất:

$\left| x \right| = x$

$\left| x \right| =  - x$

$\left| x \right| < 0$

$\left| x \right| = 0$

$1$

$2$

$3$

$4$

\(\widehat {{A_2}} = 80^\circ ;\,\widehat {{C_2}} = 110^\circ \)

\(\widehat {{A_2}} = 110^\circ ;\,\widehat {{C_2}} = 70^\circ \)                          

\(\widehat {{A_2}} = 70^\circ ;\,\widehat {{C_2}} = 110^\circ \)

\(\widehat {{A_2}} = 70^\circ ;\,\widehat {{C_2}} = 70^\circ \)

\(\widehat {MEF} = 133^\circ \)       

\(\widehat {MEI} = 47^\circ \)          

\(\widehat {IEN} = 133^\circ \)

Cả A, B, C đều đúng.

\(\dfrac{x}{a} = \dfrac{y}{b} = \dfrac{{x + y}}{{a + b}}\)

\(\dfrac{x}{a} = \dfrac{y}{b} = \dfrac{{x.y}}{{a.b}}\)

\(\dfrac{x}{a} = \dfrac{y}{b} = \dfrac{{x.y}}{{a + b}}\)

\(\dfrac{x}{a} = \dfrac{y}{b} = \dfrac{{x - y}}{{a + b}}\)

${a^m}.{a^n} = {a^{m + n}}$

${\left( {a.b} \right)^m} = {a^m}.{b^m}$

\({\left( {{a^m}} \right)^n} = {a^{m + n}}\)

${\left( {{a^m}} \right)^n} = {a^{m.n}}$