Question

Solve the following system of equations using matrices.
8x + 7y = 5
4x – 9y = 65
Answer

(5, -5)

(5, 65)

(7, -7)

(65, 5)

Answer 1

@Chubba can you help me with this one?

Answer 2

whoa nelly
\[8x+7y=5\\
4x-9y=65\] you need the method or the answer?

Answer 3

if you just want the answer, it is in this link

Answer 4

I would like the method, in order to solve it in the future. It confused me because of the matrices

Answer 5

http://www.wolframalpha.com/input/?i=8x%2B7y%3D5+and+4x-9y%3D65

Answer 6

matrix method is a pain in the neck, and worse to write
multiply the first equation by 9, the second one by 7, then add them up
the y terms will drop out

Answer 7

or if you like you can check which of the 4 solutions you are given work in both equations
that actually takes longer to do

Answer 8

So you can solve this in other ways than the question stated?

Answer 9

\[8x+7y=5\\
4x-9y=65\]
\[9(8x+7y=5)\\
7(4x-9y=65)\]

Answer 10

oh hell yes

Answer 11

Okay, I wasnt sure.

Answer 12

\[72x+63y=45\\
28x-63y=455\]

Answer 13

add and get \(100x=500\) making \(x=5\)

Answer 14

unless you have to do this in an in class exam, all of this is donkey work
why they invented computers
i would just use wolfram and get it over with in two seconds

Answer 15

sorry in algebra right now myself. and am sitting in class right now. my method would have been plugging the ordered pairs in to see which one was true. then go from there.

Answer 16

okay thanks I didn't know about that site.

Answer 17

i sent the link, note the syntax i wrote

Answer 18

and i would do that as long as there is multiple options to chose from, otherwise you should know how to work the method out.