N=2- количество лет
р=12% - процент прироста вклада
х - первоначальная сумма вклада
![x*( \frac{100+p}{100})^n=x+1272\\\\x*( \frac{100+12}{100})^2=x+1272\\\\x*1,12^2=x+1272\\1,2544x-x=1272\\0,2544x=1272\\x=1272:0,2544\\ x=5000](https://tex.z-dn.net/?f=x%2A%28+%5Cfrac%7B100%2Bp%7D%7B100%7D%29%5En%3Dx%2B1272%5C%5C%5C%5Cx%2A%28+%5Cfrac%7B100%2B12%7D%7B100%7D%29%5E2%3Dx%2B1272%5C%5C%5C%5Cx%2A1%2C12%5E2%3Dx%2B1272%5C%5C1%2C2544x-x%3D1272%5C%5C0%2C2544x%3D1272%5C%5Cx%3D1272%3A0%2C2544%5C%5C+x%3D5000)
Итак, первоначальный вклад должен составить 5000 руб.
1. A
2. D
3. B
(8x^2-4xy)/(y-2x)=(4x(2x-y))/(y-2x)=-(4x(y-2x))/(y-2x)=-4x
Х²-9х+18=х²-6х-3х+18=
х(х-6)-3(х-6)=(х-6)(х-3)
X^2-16+64=01)х^2=-12-36
x^2=-48
2)4x^2-28x+49=0
D=b^2-4ac=28^2-4*4*49=0
x=-b/2a=28:2*4=28:8=3.5
3)<span>x^2=16-64
x^2=-48
4)</span><span>9x^2+30+25
</span><span>9x^2=-30-25
</span><span>9x^2=-55
</span>x^2=-55/9
x^2=-6целых 1/9