Question

Y = 4x - 6 2x - 3y = 8 if this problem is to be solved by substitution, which is a correct step?

a.2x - 12x + 18 = 8
b.2x - 12x - 18 = 8
c.2x - 4x + 6 = 8
d.2x + 12x + 18 = 8

Answer 1

for future students it was a

Answer 2

The correct step is a.
`2x-12x+18=8`

Explanation:

Given the following linear equation system :

`\left \{ {{y=4x-6} \atop {2x-3y=8}} \right.`

One way to solve it is by substitution.

By substitution, we need to have one of the variables in term of the another.

In this exercise, we have the variable ''y'' in terms of ''x'' in the first equation :

`y=4x-6`

Given that we know this, we can replace the value of ''y'' in the second equation :

`2x-3y=8`

Replacing ⇒

`2x-3(4x-6)=8`

`2x-12x+18=8`

That it is the correct step in order to use substitution.