Question

розвязати систему рівнянь у=4-х; х²+3ху=18
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Answer 1

$\left \{ {{y=4-x} \atop {x^{2}+3xy=18 }} \right.\\\\\left \{ {{y=4-x} \atop {x^{2}+3x*(4-x)=18 }} \right. \\\\\left \{ {{y=4-x} \atop {x^{2}+12x-3x^{2}=18}} \right.\\\\\left \{ {{y=4-x} \atop {-2x^{2}+12x-18=0 }} \right.\\\\\left \{ {{y=4-x} \atop {x^{2}-6x+9=0 }} \right.\\\\\left \{ {{y=4-x} \atop {(x-3)^{2}=0 }} \right.\\\\\left \{ {{y=4-x} \atop {x-3=0}} \right.\\\\\left \{ {{x=3} \atop {y=1}} \right.\\\\Otvet:\boxed{(3 \ ; \ 1)}$