Решение в закрепленном файле.
1) b-(4-2b)+(3b-1)
b-4+2b+3b-1
6b-5
2) 4x-(1-2x)+(2x-7)
4x-1+2x+2x-7
8x-8=8(x-1)
A) (p+q+r) * (p+q-r) = p² + q² - r²;
Б) (x+1) * (x+2) * (x+3) = (x² + 2x + x + 2) * (x + 3) = (x² + 3x + 2) * (x + 3) = x³ + 3x³ + 3x³ + 9x + 2x + 6 = 7x³ + 11x + 6;
В) (m-5)*(m-3) + (4-m)² = m² - 3m - 5m + 15 + 16 - 8m + m² = 2m² - 16m + 31
α - угол четвёртой четверти, значит Cosα > 0 :
![Cos\alpha =\sqrt{1-Sin^{2}\alpha}=\sqrt{1-(-\frac{\sqrt{7}}{4})^{2}}=\sqrt{1-\frac{7}{16}}=\sqrt{\frac{9}{16}}=\frac{3}{4}](https://tex.z-dn.net/?f=Cos%5Calpha%20%3D%5Csqrt%7B1-Sin%5E%7B2%7D%5Calpha%7D%3D%5Csqrt%7B1-%28-%5Cfrac%7B%5Csqrt%7B7%7D%7D%7B4%7D%29%5E%7B2%7D%7D%3D%5Csqrt%7B1-%5Cfrac%7B7%7D%7B16%7D%7D%3D%5Csqrt%7B%5Cfrac%7B9%7D%7B16%7D%7D%3D%5Cfrac%7B3%7D%7B4%7D)
1,2х≥7
х≥7:1,2
х≥70/12
х≥5 5/6
х∈[5 5/6;+∞)