Question

L 5.2.3 Quiz: Two-Variable Systems: Substitution

Question 7 of 10
Use the substitution method to solve the system of equations. Choose the
correct ordered pair.
y = 10x-9
y = x + 18

Answer 1

We get x=3 and y=21

The ordered pair will be: (3,21)

Explanation:

We need to use the substitution method to solve the system of equations.

`y = 10x-9\\y = x + 18`

For substitution method we substitute the value of x or y from one equation to other.

Let:

`y = 10x-9--eq(1)\\y = x + 18--eq(2)`

Putting value of y from equation 2 into equation 1

`y=10x-9\\Put\:y=x+18\\x+18=10x-9\\x-10x=-9-18\\-9x=-27\\x=(-27)/(-9)\\x=3`

So, we get value of x=3

Now, for finding value of y, We substitute the value of x

Find value of x from equation 2

`y=x+18\\x=y-18`

Now, putting value of x in equation 1

`y=10x-9\\Put\:x=y-18\\y=10(y-18)-9\\y=10y-180-9\\y-10y=-189\\-9y=-189\\y=(-189)/(-9)\\y=21`

So, we get value of y=21

So, We get x=3 and y=21

The ordered pair will be: (3,21)