Объяснение:
Уравнение прямой, проходящей через 2 точки:
![\frac{x-x_1}{x_2-x_1}=\frac{y-y_1}{y_2-y_1}\; .\\\\1)\; \; A(4;-6)\; \; ,\; \; B(-8;-12)\\\\l:\; \; \frac{x-4}{-8-4}=\frac{y+6}{-12+6}\; \; \to \; \; \frac{x-4}{-12}=\frac{y+6}{-6}\; \; \to \; \; \frac{x-4}{2}=\frac{y+6}{1}\; ,\\\\x-4=2(y+6)\; \; \to \; \; x-4=2y+12\; \; ,\; \; 2y=x-16\; ,\; \; \boxed {y=\frac{1}{2}x-8}\\\\ili\\\\y=kx+b\; ,\\\\A(4;-6)\, :\; \; -6=k\cdot 4+b\; \; ,\; \; 4k+b=-6\\\\B(-8;-12)\, :\; \; -12=k\cdot (-8)+b\; \; ,\; \; \; -8k+b=-12\\\\\left \{ {{4k+b=-6} \atop {-8k+b=-12}} \right. \; \ominus \; \left \{ {{4k+b=-6} \atop {12k=6\quad }} \right. \; \; \left \{ {{b=-6-4k} \atop {k=\frac{1}{2}\qquad }} \right. \; \; \left \{ {{b=-6-2=-8} \atop {k=\frac{1}{2}\qquad \quad }} \right. \; \; \to \; \; y=\frac{1}{2}x-8](https://tex.z-dn.net/?f=%5Cfrac%7Bx-x_1%7D%7Bx_2-x_1%7D%3D%5Cfrac%7By-y_1%7D%7By_2-y_1%7D%5C%3B%20.%5C%5C%5C%5C1%29%5C%3B%20%5C%3B%20A%284%3B-6%29%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%20B%28-8%3B-12%29%5C%5C%5C%5Cl%3A%5C%3B%20%5C%3B%20%5Cfrac%7Bx-4%7D%7B-8-4%7D%3D%5Cfrac%7By%2B6%7D%7B-12%2B6%7D%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20%5Cfrac%7Bx-4%7D%7B-12%7D%3D%5Cfrac%7By%2B6%7D%7B-6%7D%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20%5Cfrac%7Bx-4%7D%7B2%7D%3D%5Cfrac%7By%2B6%7D%7B1%7D%5C%3B%20%2C%5C%5C%5C%5Cx-4%3D2%28y%2B6%29%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20x-4%3D2y%2B12%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%202y%3Dx-16%5C%3B%20%2C%5C%3B%20%5C%3B%20%5Cboxed%20%7By%3D%5Cfrac%7B1%7D%7B2%7Dx-8%7D%5C%5C%5C%5Cili%5C%5C%5C%5Cy%3Dkx%2Bb%5C%3B%20%2C%5C%5C%5C%5CA%284%3B-6%29%5C%2C%20%3A%5C%3B%20%5C%3B%20-6%3Dk%5Ccdot%204%2Bb%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%204k%2Bb%3D-6%5C%5C%5C%5CB%28-8%3B-12%29%5C%2C%20%3A%5C%3B%20%5C%3B%20-12%3Dk%5Ccdot%20%28-8%29%2Bb%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%20%5C%3B%20-8k%2Bb%3D-12%5C%5C%5C%5C%5Cleft%20%5C%7B%20%7B%7B4k%2Bb%3D-6%7D%20%5Catop%20%7B-8k%2Bb%3D-12%7D%7D%20%5Cright.%20%5C%3B%20%5Cominus%20%5C%3B%20%20%5Cleft%20%5C%7B%20%7B%7B4k%2Bb%3D-6%7D%20%5Catop%20%7B12k%3D6%5Cquad%20%7D%7D%20%5Cright.%20%5C%3B%20%5C%3B%20%5Cleft%20%5C%7B%20%7B%7Bb%3D-6-4k%7D%20%5Catop%20%7Bk%3D%5Cfrac%7B1%7D%7B2%7D%5Cqquad%20%7D%7D%20%5Cright.%20%5C%3B%20%5C%3B%20%5Cleft%20%5C%7B%20%7B%7Bb%3D-6-2%3D-8%7D%20%5Catop%20%7Bk%3D%5Cfrac%7B1%7D%7B2%7D%5Cqquad%20%5Cquad%20%7D%7D%20%5Cright.%20%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20y%3D%5Cfrac%7B1%7D%7B2%7Dx-8)
![2)\; \; l\parallel l_1\; \; \to \; \; \; k=k_1\; \; ,\; \; \; \; C\in l_1\\\\C(0;3)\, :\; \; y=\frac{1}{2}x+b\; \; ,\; \; 3=\frac{1}{2}\cdot 0+b\; \; \to \; \; b=3\\\\\boxed {l_1:\; \; y=\frac{1}{2}x+3}](https://tex.z-dn.net/?f=2%29%5C%3B%20%5C%3B%20l%5Cparallel%20l_1%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20%5C%3B%20k%3Dk_1%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%20%5C%3B%20%5C%3B%20C%5Cin%20l_1%5C%5C%5C%5CC%280%3B3%29%5C%2C%20%3A%5C%3B%20%5C%3B%20y%3D%5Cfrac%7B1%7D%7B2%7Dx%2Bb%5C%3B%20%5C%3B%20%2C%5C%3B%20%5C%3B%203%3D%5Cfrac%7B1%7D%7B2%7D%5Ccdot%200%2Bb%5C%3B%20%5C%3B%20%5Cto%20%5C%3B%20%5C%3B%20b%3D3%5C%5C%5C%5C%5Cboxed%20%7Bl_1%3A%5C%3B%20%5C%3B%20y%3D%5Cfrac%7B1%7D%7B2%7Dx%2B3%7D)
пятый член арефметической прогрессии число 3
Ответ:
-4
Объяснение:
1/а -(а+5у)/(5ау)=(5у)/(5ау) -(а+5у)/(5ау)=(5у-а-5у)/(5ау)=-а/(5ау)=-1/(5у)=-1/(5•1/20)=-20/5=-4
A+a^2-b-b^2=
(a-b)+(a^2-b^2)=
(a-b)+(a-b)(a+b)=
(a-b)*(1+a+b)