Question

resolver este sistema con la regla de cramer
5a+2b=15
2a+b=5

Answer 1

$\left \{ {{-1(5a+2b=15)} \atop {2(2a+b=5)}} \right.$

$\left \{ {{-5a-2b=-15} \atop {4a+2b=10}} \right.$ sumamos

-5a+4a=15+10

-a=25=>a=-25

reemplazando...

5a+2b=15

5(-25)+2b=15

-125+2b=15

2b=140=>b=70