Объяснение:
7х-21=7(х-3)
8х²-12х+24=4(2х²-3х+6)
13х+17х²=х(13+17х)
6х³+8х²-10х=2х(3х²+4х-5)
Вот накалякал. Разбирайся :)
xy/(x+y) = 5
xz/(x+z) = 7
yz/(y+z) = 9
xy = 5x + 5y
xz = 7x + 7z
yz = 9y + 9z
x(y-5) = 5y
x = 5y/(y-5)
5yz/(y-5) = 35y/(y-5) + 7z
5yz = 35y + 7z * (y-5)
5yz = 35y + 7yz - 35z
2yz + 35y = 35z
y(2z + 35) = 35z
y = 35z/(2z + 35) = z/(2z/35 + 1)
35z^2/(2z + 35) = 315z/(2z + 35) + 9z
35z^2 = 315z + 9z*(2z + 35)
35z^2 = 315z + 18z^2 + 315z
17z^2 = 630z
z=630/17
y = 35*630/(2*630/17 + 35)/17 = 35*630/(1260 + 595) = 22050/1855 = 630 / 53
x = 5*630/(630/53 - 5)/53 = 5*630/((630/53 - 5)*53) = 5*630/365 = 630/73
a) 7x - 21 = 7(x - 3)
б) 8x² - 12x + 24 = 4(2x² - 3x + 6)
в) 13x + 17x² = x(13 + 17x)
г) 6x³ + 8x² - 10x = 2x(3x² + 4x - 5)