Question

Use the substitution method to solve the system of equations.

4x – y = 4
x + 4y = 18

Answer 1

(1, 4) /
(4, 2) /
(4, 1) /
(2, 4)

Answer 2

what have you come up with so far?

Answer 3

i got (4, 1) ?

Answer 4

just solve for whatever you think would be easier. You can solve for y in the first equation or x in the second equation. Personally i think it'd be easier to solve for x in the second equation.
We can solve for x in the second equation by subtracting 4y from both sides
x = 18 - 4y
Now that we know that x equals, we can plug it into the first equation. We will plug in ALL of these numbers into x in the first equation which is 4x - y = 4
so, plug in the entire 18-4y into x.

4 (18-4y) - y = 4
we have to use the distributive property. 4 times 18 equals 72, 4 times negative 4y equals -16y.

72 - 16y - y = 4
let's combine like terms
72 - 17y = 4
subtract 72 from both sides
-17y = -68
divide by 17 to solve for y
y = 4
NOW that we know what y equals, let's plug it back into the equation where we found out what x equals, which is x = 18 - 4y
plug in 4
x = 18 - 4(4)
x = 18 - 16
x = 2
your solution is
(2,4)

Answer 5

:( i put thought into that :"(

Answer 6

thank you! lol, your really helpful!

Answer 7

thanks :")