Question

Giúp em 2 câu này ạ :(((((

Answer 1

Bài 4:

\(a,x=180^0-60^0-40^0=80^0\\ b,2x=\widehat{ADB}=90^0-\widehat{BAD}=70^0\\ \Rightarrow x=35^0\\ y=180^0-\widehat{ADB}=110^0\left(kề.bù\right)\)

Bài 2:

\(a,\Leftrightarrow\left[{}\begin{matrix}2x=\dfrac{1}{2}\\x=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{4}\\x=-1\end{matrix}\right.\\ b,\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{7}\\x=-\sqrt{7}\end{matrix}\right.\)

Answer 2

Bài 1:

Hình 1: \(x=180^o-60^o-40^o=80^o\)

Hình 2: 

Xét ΔABD có: \(\widehat{ADB}=180^o-90^o-20^o=70^o\)

\(y=180^o-\widehat{ADB}=180^o-70^o=110^o\)(2 góc kề bù)

Xét ΔACD có: \(x=\dfrac{180^o-y}{2}=\dfrac{180^o-110^o}{2}=35^o\)

Bài 2:

a) \(\Leftrightarrow\left[{}\begin{matrix}2x-\dfrac{1}{2}=0\\x+1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{4}\\x=-1\end{matrix}\right.\)

b) \(\Leftrightarrow\left[{}\begin{matrix}x=-\sqrt{7}\\x=\sqrt{7}\end{matrix}\right.\)