15%дети
25% ПРОСТО ЖИВУЩИХ НЕРАБОТАЮЩИХ, получаем
1)15+25=30
2)100-30=70%
3)500000/100=5000
4)5000*70=350000
11707|23
115 |509
----------
207
- 207
--------
0
А)-12а
б)-12с
в)3а
г)24х
д)-90у
е)2х
ж)- 14у
з)-16а
и)3у
к)-99с
л)-36У
м)-3с
![\displaystyle \frac{4}{1-cos^2x}-\frac{5}{sinx}=6\\\\cos^2x+sin^2x=1;\\\\ 1-cos^2x=sin^2x \\\\ODZ: sinx\neq 0; x\neq \pi n; n\in Z\\\\\frac{4}{sin^2x}-\frac{5}{sinx}=6\\\\\frac{4-5sinx-6sin^2x}{sinx}=0\\\\6sin^2x+5sinx-4=0\\\\D=25+96=121=11^2\\\\sinx=\frac{-5-11}{12}=-\frac{16}{2}\\\\sinx=\frac{-5+11}{12}=\frac{1}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle+%5Cfrac%7B4%7D%7B1-cos%5E2x%7D-%5Cfrac%7B5%7D%7Bsinx%7D%3D6%5C%5C%5C%5Ccos%5E2x%2Bsin%5E2x%3D1%3B%5C%5C%5C%5C+1-cos%5E2x%3Dsin%5E2x+%C2%A0%5C%5C%5C%5CODZ%3A+sinx%5Cneq+0%3B+x%5Cneq+%5Cpi+n%3B+n%5Cin+Z%5C%5C%5C%5C%5Cfrac%7B4%7D%7Bsin%5E2x%7D-%5Cfrac%7B5%7D%7Bsinx%7D%3D6%5C%5C%5C%5C%5Cfrac%7B4-5sinx-6sin%5E2x%7D%7Bsinx%7D%3D0%5C%5C%5C%5C6sin%5E2x%2B5sinx-4%3D0%5C%5C%5C%5CD%3D25%2B96%3D121%3D11%5E2%5C%5C%5C%5Csinx%3D%5Cfrac%7B-5-11%7D%7B12%7D%3D-%5Cfrac%7B16%7D%7B2%7D%5C%5C%5C%5Csinx%3D%5Cfrac%7B-5%2B11%7D%7B12%7D%3D%5Cfrac%7B1%7D%7B2%7D)
В первом случае решений нет
![\displaystyle sinx=\frac{1}{2}\\\\x=(-1)^n*arcsin\frac{1}{2}+\pi n; n\in Z\\\\x_1=\frac{\pi}{6}+2\pi n; n\in Z\\\\x_2=\frac{5\pi}{6}+2\pi n; n\in Z](https://tex.z-dn.net/?f=%5Cdisplaystyle+sinx%3D%5Cfrac%7B1%7D%7B2%7D%5C%5C%5C%5Cx%3D%28-1%29%5En%2Aarcsin%5Cfrac%7B1%7D%7B2%7D%2B%5Cpi+n%3B+n%5Cin+Z%5C%5C%5C%5Cx_1%3D%5Cfrac%7B%5Cpi%7D%7B6%7D%2B2%5Cpi+n%3B+n%5Cin+Z%5C%5C%5C%5Cx_2%3D%5Cfrac%7B5%5Cpi%7D%7B6%7D%2B2%5Cpi+n%3B+n%5Cin+Z)
Выбор корней:
оба корня попадают на интервал [-2π;-π/2]
найдем их
![\displaystyle x=-2\pi +\frac{\pi }{6}=\frac{-12\pi+\pi }{6}=-\frac{11\pi }{6}\\\\\ x=-2\pi+\frac{5\pi }{6}=-\frac{7\pi }{6}](https://tex.z-dn.net/?f=%5Cdisplaystyle+x%3D-2%5Cpi+%2B%5Cfrac%7B%5Cpi+%7D%7B6%7D%3D%5Cfrac%7B-12%5Cpi%2B%5Cpi+%7D%7B6%7D%3D-%5Cfrac%7B11%5Cpi+%7D%7B6%7D%5C%5C%5C%5C%5C+x%3D-2%5Cpi%2B%5Cfrac%7B5%5Cpi+%7D%7B6%7D%3D-%5Cfrac%7B7%5Cpi+%7D%7B6%7D)