Giúp mình bài này với mình cảm ơn rất nhìuuuu.
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\(=\left(4+\sqrt{15}\right)\left(\sqrt{5}-\sqrt{3}\right)\sqrt{2}\sqrt{4-\sqrt{15}}\\ =\left(4+\sqrt{15}\right)\left(\sqrt{5}-\sqrt{3}\right)\sqrt{8-2\sqrt{15}}\\ =\left(4+\sqrt{15}\right)\left(\sqrt{5}-\sqrt{3}\right)\sqrt{\left(\sqrt{5}-\sqrt{3}\right)^2}\\ =\left(4+\sqrt{15}\right)\left(\sqrt{5}-\sqrt{3}\right)\left(\sqrt{5}-\sqrt{3}\right)\\ =\left(4+\sqrt{15}\right)\left(8-2\sqrt{15}\right)\\ =32-8\sqrt{15}+8\sqrt{15}-30=2\)
\(a,ĐKXĐ:\left\{{}\begin{matrix}8-4x\ge0\\5x-10\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\le2\\x\ne2\end{matrix}\right.\Leftrightarrow x< 2\\ b,ĐKXĐ:\left\{{}\begin{matrix}\dfrac{-3}{x+2}\ge0\\x^2+2\ge0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x+2< 0\left(-3< 0;x+2\ne0\right)\\x\in R\left(x^2+2\ge2>0\right)\end{matrix}\right.\Leftrightarrow x< -2\)
Lời giải:
$\widehat{M_1}-\widehat{M_2}=\widehat{N_1}-\widehat{N_2}(1)$
$\widehat{M_1}+\widehat{M_2}=\widehat{N_1}+\widehat{N_2}(2)$ (cùng bằng $180^0$)
Lấy $(1)+(2)$ và thu gọn thì $\widehat{M_1}=\widehat{N_1}$
Mà 2 góc này ở vị trí so le trong nên $m\parallel n$
1 Nam said that he came from Thanh Hoa city
2 Mr Cuong asked me if I liked pop music
3 Although the weather was bad, we visited Bat Trang village
4 Because it was raining, they cancelled the trip to Trang An
5 We have to try harder so that our handicrafts can keep up with theirs
6 She grew up in Thanh Hoa city
II
1 Eventhough it was very cold out, we decided to go for a walk
2 Mai studied hard for the exam so that she could have good marks
1. nam said that he came from Thanh Hoa city.
2.Mr. Cuong asked if I liked pop music
3. although the weather was bad, we visited bat Trang village