Question

Знайдіть розв°язки системи рівнять 1) {5u+4v=11 ; u+6v=-3 2) {2a-5b=9 ; a-7b=0

Answer 1

$\left \{ {5u+4v=11} \atop {u+6v=-3}|*(-5)} \right. \\\\+\left \{ {{5u+4v=11} \atop {-5u-30v=15}} \right.\\ -------\\-26u=26\\u=-1\\5*(-1)+4v=11\\4v=16\\v=4$

ответ : (-1 ; 4)

$2)\left \{ {{2a-5b=9} \atop {a-7b=0}} \right.\\\\\left \{ {{a=7b} \atop {2*7b-5b=9}} \right.\\\\\left \{ {{a=7b} \atop {14b-5b=9}} \right.\\\\\left \{ {{a=7b} \atop {9b=9}} \right.\\\\\left \{ {{b=1} \atop {a=7}} \right.$

ответ : (7 , 1)