Х²-9х+20=0
х₁+х₂= 9
х₁ * х₂ =20
х₁=5
х₂=4
3 х 1/3 = 1
-2 х -2 = 4
1-4=-3
Ответ: -3
Решение
1) (a + 3)/(a - 1) + (a + 5)/(2 - 2a) = <span>(a + 3)/(a - 1) - (a + 5)/[2*(a - 1)] =
(2a + 6 - a - 5) / </span>[2*(a - 1)] = (a + 1) / [2*(a - 1)]<span>
2) (2x - y) /(2x + y) + y/(4x + 2y) = </span><span> (2x - y) /(2x + y) + y / ]2*(2x + y)] =
(4x - 2y + y) / </span>]2*(2x + y)] = = (4x - y) / <span>]2*(2x + y)] </span>
<span>3-3a при a =1и a = -1
</span>3-3*1=0
3-3*(-1)=6
X^2-y=8
y+x=-2
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x^2-y=8
x=-2-y
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(-2-y)^2-y=8
x=-2-y
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4+4y+y^2-y=8
x=-2-y
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y^2+3y-4=0
x=-2-y
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y1=-4; y2=1
x=-2-y
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y1=-4; y2=1
x1=2; x2=-3
ответ: (2; -4) (-3; 1)