Question

What method would you use for this system of linear equations? why?

x= 2y-7
y - 3x = -9

Answer 1

`x=5`

`y=6`

Explanation:

Linear equations can be solved by using method of substitution.

`x= 2y-7` ------> equation 1
`y - 3x = -9` ------> equation 2

Substitute equation 1 in equation 2 as shown below:

`y-3x=-9`

`y-3(2y-7) = -9`

`y-6y+21 = -9`

Simplify further to get value of `y` by making `y` the subject.

`-5y=-9-21`

`-5y=-30`

`y=(-30)/-5` = `30/5` =`6`

`y=6`

Substitute value of `y` in equation 1

`x= 2y-7` ------> equation 1

`x=2(6)-7`

`x=12-7`

`x=5`

Checking the answer:
`y - 3x = -9` ------> equation 2
`6-3(5) =-9`
`6-15=-9`----> Correct!