Question

If you were to solve the following system by substitution, what would be the best

variable to solve for and from what equation?
2x+8v=12
3r- 8v=11

Answer 1

x, In the first equation.

Explanation:

Answer 2

To solve the two equations simultaneously using the substitution method we need to rearrange one of the equation to make either
`'x'` or
`'y'` the subject.

We can try in turn rearranging both equations and see which unknown term would have been easier to solve first

Equation
`2x+8y=12`

Making
`'x'` the subject

`2x=12-8y` , dividing each term by 2

`x=6-4y`⇒ (Option 1)

Making
`'y'` the subject

`8y=12-2x`, multiply each term by 8 gives

`y= (12)/(8) - (2)/(8)x`⇒ (Option 2)

Equation
`3x-8y=11`
Making
`'x'` the subject

`3x=11+8y`, divide each term by 3

`x= (11)/(3)+ (8)/(3)y` ⇒ (Option 3)

Making
`'y'` the subject

`8y=3x-11`, divide each term by 8

`y= (3)/(8)x- (11)/(8)` ⇒ (Option 4)

From all the possibilities of rearranged term, the most efficient option would have been the first option, from equation
`2x+8y=12` with
`'x'` as the subject,
`x=6-4y`