How do you solve the following linear system: x + 6y = 28 , 6x - 5y = -1 ?

1 Answer
Apr 12, 2018

See below

Explanation:

We will use elimination to solve this linear system.

Firstly we need to get same numbers but opposite sign from that same number.

In x + 6y=28 /* (-6) (multiply the first equation with -6)
6x-5y=-1

We get,

color(blue)(-6x)-36y=-168 ------- color (red) (equation 1
color(blue)(6x)-5y=-1 ------ color(blue)(equation 2)

You can see that -6x and 6x are opposites so we cancel them but firstly write the following,

cancel(-6x)-36y+cancel(6x)-5y=-168-1

-41y=-169 From here

y=-169/-41

y=169/41

It's now

-6x-36y=-168 ------- color (red) (equation 1
y=169/41 ------ color(blue)(equation 2)

Basically just add y=169/41 into y in the first equation

-6x-36*169/41=-168

-6x-6084/41=-168

-6x=-168+6084/41

-6x=-804/41

x=(804/41)/(6/1)

x=cancel804/cancel246

x=134/41

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Final result:

x= 134/41

y=169/41