Question

Решите систему неравенств.
1)4х-2y=-6
3x-3y=9
2)x+y=5
x(в кв.)+y( в кв.)=6

Answer 1

$left {{{4x-2y=-6|:2}atop {3x-3y=9|:3}}right.\\left{{{2x-y=-3}atop {x-y=3}}right.\\left {{{y=2x+3} atop {x-2x-3=3}}right.\\left{{{y=2x+3}atop{-x-3=3}}right.\\left{{{y=2x+3}atop{x=-6}} right.\\left{{{y=2(-6)+3} atop {x=-6}} right.\\left {{{y=-12+3}atop{x=-6}} right.\\left{ {{y=9} atop {x=-6}} right.\\(-6;9)$

$left {{{x+y=5}atop {x^2+y^2=6}} right.\\left{{{x=5-y}atop {(5-y)^2+y^2=6}}right.\\(5-y)^2+y^2=6\25-10y+y^2+y^2-6=0\2y^2-10y+19=0\D=(-10)^2-4*2*19=100-152=-52<0$
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