Question

How do you solve the following system?: `3x +y =15 , -9x +8y = 4`

Answer 1

There are many ways to solve this.I'm using substitution method.
lets see:

Explanation:

`3x+y=15`
`impliesy=15-3x(equation 1)`

putting the value of y in equation 2
`-9x+8(15-3x)=4`
`implies-9x+120-24x=4`
`implies-33x=-116`
`impliesx=(-116)/-33`
`impliesx=3.51`

putting the value of x in equation 1
`y=15-3*3.51`
`impliesy=15-10.53`
`impliesy=4.47`

`therefore x=3.51 and y=4.47`