Question

resolva o sistema aplicando a regra de cramer e assinale a alternativa correta :

{3x+y=7
-x+7y=5}

a- V=[{5,3}]
b- V=[{2,1}]
c- V=[{1,2}]
d- V=[{3,1}]
e- V=[{1,3}]
e

Answer 1

.
$\left \{ {{3x+y=7} \atop {-x+7y=5}} \right.$

$D= \left[\begin{array}{ccc}3&1\\-1&7\\\end{array}\right] =21+1=22$

$Dx= \left[\begin{array}{ccc}7&1\\5&7\\\end{array}\right] =49-5=44$

$Dy= \left[\begin{array}{ccc}3&7\\-1&5\\\end{array}\right] =15+7=22$

$x= \frac{Dx}{D} = \frac{44}{22} =2 \\ \\ y= \frac{Dy}{D} = \frac{22}{22} =1$

V={(2,1)}    Letra B