Question

For the following system, if you isolated x in the first equation to use the Substitution Method, what expression would you substitute into the second equation?

-x + 2y = -6
3x + y = 8

Answer
2y - 6
-2y + 6
-2y - 6
2y + 6

Answer 1

x = 2y + 6 =3.14

Explanation:

for substitution method

-x + 2y = -6 ........................................................(1)

3x + y = 8 ........................................................(2)

make x the subject of the equation 1 by isolating it

x = 2y + 6 ........................................................(3)

substitute eqn 3 in 2

3(2y + 6) + y = 8 ........................................................(4)

6y + 18 + y = 8

7y = 8-18=-10

y= -10/7 = -1.43

x= 2(-10/7) + 6 =-2.86 +6 = 3.14

to confirm the answer, we input the value of x and y in equation 1 and 2

Answer 2

The answer is 2y + 6

-x + 2y = -6
3x + y = 8

Let's isolate x in the first equation:
-x = - 2y - 6

Now, multiply both sides by (-1)
x = 2y + 6