Question

Use Cramer's Rule to solve the linear system:
x-y=7
3x+2y=6

Answer 1

happy feet!!!!!!! can you help me out with a problem

Answer 2

where are you so far?

Answer 3

I don't know where to start

Answer 4

I knwow cramer's rule

Answer 5

but, I haven't used cramer's rule to solve linear expressions yet

Answer 6

the matrix you can form from that is \[A = \left[\begin{matrix}1&-1\\3&2\end{matrix}\right]\] and b = \(\left[\begin{matrix}7\\6\end{matrix}\right]\)
tell me det (A) =?

Answer 7

ok, this is what you do

Answer 8

1(2)-(-1)(3)=2+3=5

Answer 9

yup

Answer 10

so det(a) equal 5, right?

Answer 11

now, replace b into the first column of A, you get a new matrix, let say it 's A1, calculate det (A1) , what do you have?

Answer 12

20?

Answer 13

cause 7(2)-(-1)(6)=20

Answer 14

yup, then det(A1)/det(A) = ?

Answer 15

4 :)

Answer 16

hihihi, that's x. So, you get x =4
now , do the same, but this time, replace b into the second column of A, let say it's A2, take its det, and det(A2)/detA you get y =

Answer 17

-3

Answer 18

:)?

Answer 19

you see, your problem is