Question

What is the resulting equation when the expression for y in the second equation is substituted into the first equation?

3x + y = 1
y = 6 - 4x

a. -x + 6 = 1
b. x + 6 = 1
c. 7x + 6 = 1

Answer 1

3x + y = 1

3x + (6 - 4x) = 1

3x + 6 -4x = 1

3x - 4x + 6 = 1

-x + 6 = 1

Therefore (a)

Answer 2

When expression for y in the second equation is substituted into the first equation than the resulting equation -x + 6 = 1 .

Option (a) is correct .

Explanation:

As given the equations in the questions are

3x + y = 1

y = 6 - 4x

As expression for y in the second equation is substituted into the first equation .

i.e put y = 6 - 4x in 3x + y = 1 .

3x + 6 - 4x = 1

Solving the above

-x + 6 = 1

Therefore the when expression for y in the second equation is substituted into the first equation than the resulting equation -x + 6 = 1 .

Option (a) is correct .