4) ОДЗ: 7+2х>0 , 2x>-7 , x>-7/2 , x>-3,5
7=7+2x , x=0.
5) ОДЗ:
0 , (x-\sqrt{3})(x+\sqrt{3})>0, " alt="x^{2}-3>0 , (x-\sqrt{3})(x+\sqrt{3})>0, " align="absmiddle" class="latex-formula">
xпринадл.
2x>0 , x>0
Окончательно ОДЗ: х принадл.
х=-1 не входит в ОДЗ.
Ответ:х=3.
7) ...
Заданному промежутку принадлежит угол П/6.
2)Левая часть равенства =![\frac{2a}{a+4}+(\frac{4}{(a-4)^{2}}-\frac{4}{(a-4)(a+4)})\cdot{\frac{(a-4)^{2}}{4}}=\\=\frac{2a}{a+4}+\frac{4a+16-4a+16}{(a-4)^{2}(a+4)}\cdot{\frac{(a-4)^{2}}{4}=\frac{2a}{a+4}+\frac{8}{a+4}=\frac{2a+8}{a+4}=\frac{2(a+4)}{a+4}=2 \frac{2a}{a+4}+(\frac{4}{(a-4)^{2}}-\frac{4}{(a-4)(a+4)})\cdot{\frac{(a-4)^{2}}{4}}=\\=\frac{2a}{a+4}+\frac{4a+16-4a+16}{(a-4)^{2}(a+4)}\cdot{\frac{(a-4)^{2}}{4}=\frac{2a}{a+4}+\frac{8}{a+4}=\frac{2a+8}{a+4}=\frac{2(a+4)}{a+4}=2](https://tex.z-dn.net/?f=%5Cfrac%7B2a%7D%7Ba%2B4%7D%2B%28%5Cfrac%7B4%7D%7B%28a-4%29%5E%7B2%7D%7D-%5Cfrac%7B4%7D%7B%28a-4%29%28a%2B4%29%7D%29%5Ccdot%7B%5Cfrac%7B%28a-4%29%5E%7B2%7D%7D%7B4%7D%7D%3D%5C%5C%3D%5Cfrac%7B2a%7D%7Ba%2B4%7D%2B%5Cfrac%7B4a%2B16-4a%2B16%7D%7B%28a-4%29%5E%7B2%7D%28a%2B4%29%7D%5Ccdot%7B%5Cfrac%7B%28a-4%29%5E%7B2%7D%7D%7B4%7D%3D%5Cfrac%7B2a%7D%7Ba%2B4%7D%2B%5Cfrac%7B8%7D%7Ba%2B4%7D%3D%5Cfrac%7B2a%2B8%7D%7Ba%2B4%7D%3D%5Cfrac%7B2%28a%2B4%29%7D%7Ba%2B4%7D%3D2)