Думаю це правильно)))))))))
1) Упростим выражение в числителе:
![\dfrac{m-n}{2m-n}-\dfrac{m^2+n^2+m}{2m^2+mn-n^2}=\dfrac{m-n}{2m-n}-\dfrac{m^2+n^2+m}{(2m-n)(m+n)}=\\=\dfrac{m^2-n^2-m^2-n^2-m}{(2m-n)(m+n)}=\dfrac{-(2n^2+m)}{(2m-n)(m+n)};](https://tex.z-dn.net/?f=%5Cdfrac%7Bm-n%7D%7B2m-n%7D-%5Cdfrac%7Bm%5E2%2Bn%5E2%2Bm%7D%7B2m%5E2%2Bmn-n%5E2%7D%3D%5Cdfrac%7Bm-n%7D%7B2m-n%7D-%5Cdfrac%7Bm%5E2%2Bn%5E2%2Bm%7D%7B%282m-n%29%28m%2Bn%29%7D%3D%5C%5C%3D%5Cdfrac%7Bm%5E2-n%5E2-m%5E2-n%5E2-m%7D%7B%282m-n%29%28m%2Bn%29%7D%3D%5Cdfrac%7B-%282n%5E2%2Bm%29%7D%7B%282m-n%29%28m%2Bn%29%7D%3B)
2) Упростим выражение в знаменателе:
![\dfrac{4n^4+4mn^2+m^2}{2n^2+m}=\dfrac{(2n^2+m)^2}{2n^2+m}=2n^2+m;](https://tex.z-dn.net/?f=%5Cdfrac%7B4n%5E4%2B4mn%5E2%2Bm%5E2%7D%7B2n%5E2%2Bm%7D%3D%5Cdfrac%7B%282n%5E2%2Bm%29%5E2%7D%7B2n%5E2%2Bm%7D%3D2n%5E2%2Bm%3B)
3) Разложим на множители многочлен - множитель за дробью:
![n^2+n+mn+m=n(n+1)+m(n+1)=(n+1)(m+n);](https://tex.z-dn.net/?f=n%5E2%2Bn%2Bmn%2Bm%3Dn%28n%2B1%29%2Bm%28n%2B1%29%3D%28n%2B1%29%28m%2Bn%29%3B)
4) Расставим полученные результаты в исходное дробное выражение:
![\dfrac{-(2n^2+m)}{(2m-n)(m+n)}:(2n^2+m)*(n+1)(m+n)=\\= \dfrac{-(2n^2+m)}{(2m-n)(m+n)}*\dfrac{(n+1)(m+n)}{2n^2+m}=\\= -\dfrac{n+1}{2m-n}=\dfrac{n+1}{n-2m}.\\\\ Ombem:\ \dfrac{n+1}{n-2m}.](https://tex.z-dn.net/?f=%5Cdfrac%7B-%282n%5E2%2Bm%29%7D%7B%282m-n%29%28m%2Bn%29%7D%3A%282n%5E2%2Bm%29%2A%28n%2B1%29%28m%2Bn%29%3D%5C%5C%3D+%5Cdfrac%7B-%282n%5E2%2Bm%29%7D%7B%282m-n%29%28m%2Bn%29%7D%2A%5Cdfrac%7B%28n%2B1%29%28m%2Bn%29%7D%7B2n%5E2%2Bm%7D%3D%5C%5C%3D+-%5Cdfrac%7Bn%2B1%7D%7B2m-n%7D%3D%5Cdfrac%7Bn%2B1%7D%7Bn-2m%7D.%5C%5C%5C%5C+Ombem%3A%5C+%5Cdfrac%7Bn%2B1%7D%7Bn-2m%7D.)
Вторая координата вершины должна быть равна нулю, т. е. -D/4a = 0
b^2=4ac
b^2=144
b=12
График первого уравнения, не очень уверена)