![a^3-b^3=(a-b)(a^2+ab+b^2)](https://tex.z-dn.net/?f=a%5E3-b%5E3%3D%28a-b%29%28a%5E2%2Bab%2Bb%5E2%29)
1)
![(2x+y)^3-x^3=(2x+y-x)(4x^2+2xy+y^2)= \\ \\ =(x+y)(4x^2+2xy+y^2)](https://tex.z-dn.net/?f=%282x%2By%29%5E3-x%5E3%3D%282x%2By-x%29%284x%5E2%2B2xy%2By%5E2%29%3D+%5C%5C++%5C%5C+%3D%28x%2By%29%284x%5E2%2B2xy%2By%5E2%29)
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2)
![8p^3-(p+1)^3=(2p)^3-(p+1)^3= \\ \\ =(2p-(p+1))(4p^2+2p(p+1)+(p+1)^2)= \\ \\ =(p+1)(4p^2+2p^2+2p+p^2+2p+1)= \\ \\ =(p+1)(7p^2+4p+1)](https://tex.z-dn.net/?f=8p%5E3-%28p%2B1%29%5E3%3D%282p%29%5E3-%28p%2B1%29%5E3%3D+%5C%5C++%5C%5C+%3D%282p-%28p%2B1%29%29%284p%5E2%2B2p%28p%2B1%29%2B%28p%2B1%29%5E2%29%3D+%5C%5C++%5C%5C+%3D%28p%2B1%29%284p%5E2%2B2p%5E2%2B2p%2Bp%5E2%2B2p%2B1%29%3D+%5C%5C++%5C%5C+%3D%28p%2B1%29%287p%5E2%2B4p%2B1%29)
(3х^2 +4)^2 -10(3х^2 +4)+21=0
Пусть у=3х^2 +4, тогда:
у^2 -10у+21=0
D=100-84=16
у1=(10-4)/2=6/2=3
у2=(10+4)/2=14/2=7
3=3х^2 +4
3х^2=3-4
х^2=-1/3 - квадрат любого числа не должен быть отрицательным.
7=3х^2 +4
3х^2=7-4
х^2=3/3
х=1
(3x-2)/5 = (2x-3)/4 |*20
4(3x-2)=5(2x-3)
12x-8=10x-15
12x-10x=8-15
2x=-7
x=-7:2
x=-3,5
56m^2n5------35mn^5 = 8m------ 5
Оооооо да ты попала..................................