Question

Решите способом сложения:{5x-3y=9 и {7x+2y=3
Плиииз подскажите ​

Answer 1

$\displaystyle\bf\\\left \{ {{5x-3y=9} |\cdot2\atop {7x+2y=3}|\cdot3} \right. \\\\\\+\left \{ {{10x-6y=18} \atop {21x+6y=9}} \right. \\----------\\31x=27\\\\x=\frac{27}{31} \\\\2y=3-7x=3-7\cdot\frac{27}{31} =3-\frac{189}{31} =3-6\frac{3}{31} =-3\frac{3}{31} \\\\\\y=-3\frac{3}{31} :2=-\frac{96}{31} \cdot\frac{1}{2} =-\frac{48}{31} =-1\frac{17}{31} \\\\Otvet:\Big(\frac{27}{31} \ ; \ -1\frac{17}{31} \Big)$