Question

Medal!

Trevor solved the system of equations below. What mistake did he make in his work?

2x + y = 5
x − 2y = 10

y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10
5x = 0
x = 0

2(0) + y = 5
y = 5

He should have substituted 5 + 2x
He combined like terms incorrectly, it should have been 4x instead of 5x
He subtracted 10 from the right side instead of adding 10 to the right side
He made no mistake

Answer 1

Which do you think is the correct answer? Any ideas?

Answer 2

5x-10=10
5x= 10+10
5x= 20

Answer 3

i would like to learn it and then find the answer.

Answer 4

x= 20/4
x=5

Answer 5

sorry
x=20/5
x=4

Answer 6

im very confuse

Answer 7

Are there any answers from the multiple choice ones that you can eliminate? For example, look at A:
He should have substituted 5+2x for y

Should he have done this, or would this have been an incorrect step?

Answer 8

u did the mistake in fifth line

Answer 9

A) He should have substituted 5 + 2x
B)He combined like terms incorrectly, it should have been 4x instead of 5x
C)He subtracted 10 from the right side instead of adding 10 to the right side
D) He made no mistake

Answer 10

5x-10 =10
next line is wrong

Answer 11

?

Answer 12

add both sides 10
what do u get

Answer 13

20

Answer 14

5x-10+10=10+10
5x= 20
is it clear

Answer 15

@Buttercup214 : I'd suggest, seriously, that you working on solving this system of equations yourself. If you can do that correctly (and this is a skill you must learn), you should have no trouble finding Trevor's mistake.

2x + y = 5
x − 2y = 10

Answer 16

um ok

Answer 17

Have you begun your solution yet? You can always ask clarifying questions if you like.

Answer 18

its ok i found the answer.