Решала системой...
х+4у=-5
х+у=-5
1.х+4у=-5
х=-5-4у
2.-5-4у+у=-5
-5-3у=-5
-3у=0
3.х+у=-5
х=-5
Ответ.(-5:0)
X^3 - 5x^2 + 5x^2 - 25x + 6x - 30 = 0
(x - 5)(x^2 + 5x + 6) = 0
(x - 5)(x + 2)(x + 3) = 0
x1 = 5, x2 = -2, x3 = -3
0,5х + 2/3(х + 4) = 12
1/2х + 2/3х + 8/3 = 12 Общий знаменатель 6
3х + 4х + 16 = 72
7х = 72 - 16
7х = 56
х = 8
X^2(9x^2-40x+16)=0
D=1600-4*9*16=1024
x=40+-32 деленное на 18
x1=40+32/18=4
x2=8/18
x^2=0