Question

Solve the system of equations by substitution. What is the solution for x?

2x + y = 1
4x + 2y = −2

x = 0
x = 2
There is no x value, as there is no solution. - This one
x can be any value, as there is an infinite number of solutions.

Answer 1

hint: multiply the first equation by 2

Answer 2

ok thanks

Answer 3

let me know if you get stuck

Answer 4

i got 2x+y=2, so x would be 2? right

Answer 5

nope

Answer 6

i substituted what i needed to?

Answer 7

what is 2x * 2?

Answer 8

4x

Answer 9

good, what is y * 2?

Answer 10

isnt it 2y

Answer 11

good

so that gives us:

4x + 2y = 2
4x + 2y = -2

Answer 12

now subtract the two equations

let me know what you get

Answer 13

x= 1/4 and y=-3/2

Answer 14

??????

Answer 15

no?

Answer 16

what is 4x - 4x?

Answer 17

0 of course

Answer 18

good

now what is 2y - 2y?

Answer 19

0

Answer 20

good

what about 2 - (-2)?

Answer 21

4?

Answer 22

good!

so that gives us:

0 = -4

which has no solution

Answer 23

ohh ok thank you so much i did consider that but wasnt sure!

Answer 24

so its c!

Answer 25

Vocaloid has just given you the elimination method. Here is another method but it's by substitution (which is also what the question wants)

2x + y = 1
4x + 2y = −2

Rearrange the first equation so that y is on one side:
y=1-2x

That is the value for y, so you can plug that in for your second equation:
4x + 2(1-2x) = -2

Expand:
4x+2-4x=-2

Simplify:
2=-2

Obviously this is incorrect so the answer is C.