Question

Using Cramer's rule, what is the value of x in the system of equations below?

-x-3y=-3
-2x-5y=-8
a.| -3 -3 |
|_ -8-5_|=-2
-1
b.| -3 -3 |
|_-8-5_|=9
-1
c.| -1 -3 |
|_-2 -8_|=-2
-1
d.| -1 -3 |
|_-2-8_|=9
-1

Answer 1

`\left\{\begin{array}{ccc}-x-3y=-3\\-2x-5y=-8\end{array}\right\\\\\left|\begin{array}{ccc}-1&-3\\-2&-5\end{array}\right|=(-1)(-5)-(-2)(-3)=5-6=-1\\\\\left|\begin{array}{ccc}-3&-3\\-8&-5\end{array}\right|=(-3)(-5)-(-8)(-3)=15-24=-9\\\\x=(-9)/(-1)=9`

I think. It's your answer b.