Respuesta :
[tex]2x+y=5 \\
x-2y=10 \\ \\
y=5-2x \\
x-2(5-2x)=10 \\
x-10+4x=10 \\
5x-10=10 \\
\boxed{5x=0} \Leftarrow \hbox{the mistake, it should be 5x=20} \\
x=0 \\ \\
2(0)+y=5 \\
y=5[/tex]
If 2x+y=5, then y=5-2x, so he substituted 5-2x correctly.
x+4x=5x, so he combined like terms correctly.
If 5x-10=10, then 5x=10+10 -> 5x=20, so he subtracted 10 from the right side instead of adding 10 to the right side.
The answer is C.
Here's the correct solution:
[tex]2x+y=5 \\ x-2y=10 \\ \\ y=5-2x \\ x-2(5-2x)=10 \\ x-10+4x=10 \\ 5x-10=10 \\ 5x=10+10 \\ 5x=20 \\ x=\frac{20}{5} \\ x=4 \\ \\ y=5-2x \\ y=5 - 2 \times 4 \\ y=5-8 \\ y=-3 \\ \\ (x,y)=(4,-3)[/tex]
If 2x+y=5, then y=5-2x, so he substituted 5-2x correctly.
x+4x=5x, so he combined like terms correctly.
If 5x-10=10, then 5x=10+10 -> 5x=20, so he subtracted 10 from the right side instead of adding 10 to the right side.
The answer is C.
Here's the correct solution:
[tex]2x+y=5 \\ x-2y=10 \\ \\ y=5-2x \\ x-2(5-2x)=10 \\ x-10+4x=10 \\ 5x-10=10 \\ 5x=10+10 \\ 5x=20 \\ x=\frac{20}{5} \\ x=4 \\ \\ y=5-2x \\ y=5 - 2 \times 4 \\ y=5-8 \\ y=-3 \\ \\ (x,y)=(4,-3)[/tex]